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Sample records for nmr studies provide

  1. NMR studies of metalloproteins.

    Science.gov (United States)

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has long been used as an invaluable tool for structure and dynamic studies of macromolecules. Here we focus on the application of NMR spectroscopy in characterization of metalloproteins, including structural studies and identification of metal coordination spheres by hetero-/homo-nuclear metal NMR spectroscopy. Paramagnetic NMR as well as (13)C directly detected protonless NMR spectroscopy will also be addressed for application to paramagnetic metalloproteins. Moreover, these techniques offer great potential for studies of other non-metal binding macromolecules.

  2. NMR Dynamic Studies in Living Systems

    Institute of Scientific and Technical Information of China (English)

    闫永彬; 范明杰; 罗雪春; 张日清

    2002-01-01

    Nuclear magnetic resonance (NMR) can noninvasively monitor the intracellular concentrations and kinetic properties of numerous inorganic and organic compounds. These characteristics have made NMR a useful tool for dynamic studies of living systems. Applications of NMR to living systems have successfully extended to many areas, including studies of metabolic regulation, ion transport, and intracellular reaction rates in vivo. The major purpose of this review is to summarize the results that can be obtained by modern NMR techniques in living systems. With the advances of new techniques, NMR measurements of various nuclides have been performed for specific physiological purposes. Although some technical problems still remain and there are still discrepancies between NMR and traditional biochemical results, the abundant and unique information obtained from NMR spectra suggests that NMR will be more extensively applied in future studies of living systems. The fast development of these new techniques is providing many new NMR applications in living systems, as well as in structural biology.

  3. NMR studies of metalloproteins

    OpenAIRE

    Li, H; H. Sun

    2011-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has...

  4. NMR Studies of 3-Acylcamphor

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    NMR studies of some chiral 3-acyclcamphor were conducted.A complete assignment was given to 3-(4-pyridyl)carbonylcamphor by the 2D NMR technology.Assignments were also given to other b -diketones.The results showed that those 3-acylcamphors exist in the enol forms,while 2-benzoyl menthone exists in diketon form.

  5. NMR metabolomics for soil analysis provide complementary, orthogonal data to MIR and traditional soil chemistry approaches--a land use study.

    Science.gov (United States)

    Rochfort, Simone; Ezernieks, Vilnis; Mele, Pauline; Kitching, Matt

    2015-09-01

    The present study was designed to analyse soils by different methodologies to determine the range of traits that could be investigated for the study of environmental soil samples. Proton nuclear magnetic resonance spectroscopy ((1) H NMR) was employed for metametabolomic analysis of soils from agricultural systems (managed) or from soils in a native state (remnant). The metabolomic methodologies employed (grinding and extraction with sonication) are capable of breaking up cell walls and so enabled characterisation of both extracellular and intracellular components of soil. Diffuse mid-infrared spectroscopy (MIR) data was obtained for the same sample sets, and in addition, elemental composition was determined by conventional laboratory chemical testing methods. Also investigated was the antibiotic activity of the soil extracts. Resilient or suppressive soils are valued in the agricultural setting as they convey disease resistance (against bacterial and fungal pathogens) to crop plants. In order to test if any such biological activity could be detected in the soils, the extracts were tested against the bacteria Bacillus subtilis. Several extracts showed strong growth inhibition against the bacteria with the most active clustered together in principle component analysis (PCA) of the metabolomic data. The study showed that the NMR metabolomic approach corresponds more accurately to land use and biochemical properties potentially associated with suppression, while MIR data correlated well to inorganic chemical analysis. Thus, the study demonstrates the utility in combining these spectroscopic methods for soil analysis. Copyright © 2015 John Wiley & Sons, Ltd.

  6. {sup 13}CHD{sub 2}–CEST NMR spectroscopy provides an avenue for studies of conformational exchange in high molecular weight proteins

    Energy Technology Data Exchange (ETDEWEB)

    Rennella, Enrico; Huang, Rui; Velyvis, Algirdas; Kay, Lewis E., E-mail: kay@pound.med.utoronto.ca [The University of Toronto, Departments of Molecular Genetics, Biochemistry and Chemistry (Canada)

    2015-10-15

    An NMR experiment for quantifying slow (millisecond) time-scale exchange processes involving the interconversion between visible ground state and invisible, conformationally excited state conformers is presented. The approach exploits chemical exchange saturation transfer (CEST) and makes use of {sup 13}CHD{sub 2} methyl group probes that can be readily incorporated into otherwise highly deuterated proteins. The methodology is validated with an application to a G48A Fyn SH3 domain that exchanges between a folded conformation and a sparsely populated and transiently formed unfolded ensemble. Experiments on a number of different protein systems, including a 360 kDa half-proteasome, establish that the sensitivity of this {sup 13}CHD{sub 2}{sup 13}C–CEST technique can be upwards of a factor of 5 times higher than for a previously published {sup 13}CH{sub 3}{sup 13}C–CEST approach (Bouvignies and Kay in J Biomol NMR 53:303–310, 2012), suggesting that the methodology will be powerful for studies of conformational exchange in high molecular weight proteins.

  7. NMR structural studies on antifreeze proteins.

    Science.gov (United States)

    Sönnichsen, F D; Davies, P L; Sykes, B D

    1998-01-01

    Antifreeze proteins (AFPs) are a structurally diverse class of proteins that bind to ice and inhibit its growth in a noncolligative manner. This adsorption-inhibition mechanism operating at the ice surface results in a lowering of the (nonequilibrium) freezing point below the melting point. A lowering of approximately 1 degree C, which is sufficient to prevent fish from freezing in ice-laden seawater, requires millimolar AFP levels in the blood. The solubility of AFPs at these millimolar concentrations and the small size of the AFPs (typically 3-15 kDa) make them ideal subjects for NMR analysis. Although fish AFPs are naturally abundant, seasonal expression, restricted access to polar fishes, and difficulties in separating numerous similar isoforms have made protein expression the method of choice for producing AFPs for structural studies. Expression of recombinant AFPs has also facilitated NMR analysis by permitting isotopic labeling with 15N and 13C and has permitted mutations to be made to help with the interpretation of NMR data. NMR analysis has recently solved two AFP structures and provided valuable information about the disposition of ice-binding side chains in a third. The potential exists to solve other AFP structures, including the newly described insect AFPs, and to use solid-state NMR techniques to address fundamental questions about the nature of the interaction between AFPs and ice.

  8. NMR studies of isotopically labeled RNA

    Energy Technology Data Exchange (ETDEWEB)

    Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

    1994-12-01

    In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

  9. Dihydroflavanonols from Cedrus deodara, A (13)C NMR study.

    Science.gov (United States)

    Agrawal, P K; Agarwal, S K; Rastogi, R P; Osterdahal, B G

    1981-09-01

    High resolution (13)C NMR study of taxifolin, cedeodarin, cedrin and their methyl ethers allowed unambiguous placement of the Me in 5,7-dihydroxyflavanonol nucleus, besides providing other valuable information on the substitution pattern in the molecule.

  10. NMR studies of multiphase flows II

    Energy Technology Data Exchange (ETDEWEB)

    Altobelli, S.A.; Caprihan, A.; Fukushima, E. [Lovelace Institutes, Albuquerque, NM (United States)] [and others

    1995-12-31

    NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

  11. NMR studies of actinide dioxides

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)], E-mail: tokunaga.yo@jaea.go.jp; Sakai, H.; Fujimoto, T.; Kambe, S.; Walstedt, R.E.; Ikushima, K.; Yasuoka, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Aoki, D.; Homma, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Haga, Y.; Matsuda, T.D.; Ikeda, S.; Yamamoto, E.; Nakamura, A. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Shiokawa, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nakajima, K.; Arai, Y. [Department of Nuclear Energy System, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2007-10-11

    {sup 17}O NMR measurements have been performed on a series of the actinide dioxides, UO{sub 2}, NpO{sub 2} and PuO{sub 2}. Although the {sup 17}O NMR spectra in these materials are similar at higher temperatures, the low-temperature spectra present are significantly different. In UO{sub 2} we have observed a wide spectrum, forming a rectangular shape below T{sub N}=30 K. In NpO{sub 2}, on the other hand, the spectra broaden rather gradually and exhibit a two-peak structure below T{sub 0}=26 K. In PuO{sub 2}, neither spectrum broadening nor splitting has been observed. We show that these NMR spectra clearly indicate the different nature of the low-temperature magnetic ground states in these actinide compounds.

  12. NMR study of magnetism and superparamagnetism

    Science.gov (United States)

    Yuan, Shaojie

    behavior. The magnetic shape memory alloys Ni-Mn-Sn exhibit interesting properties including, field induced transformations, conventional and inverse magnetocaloric effects. They have potential for use as sensors, actuators and energy conversion devices. The Heusler alloy, Ni50Mn50-xSnx with x = 10 is one of these materials. It undergoes a transition from an austenite phase to a martensitic phase at 400 K, with the emergence of rich interesting magnetic properties below the transition. Coexistence of ferromagnetic (F) and AF spin configurations is reported in these compounds. 55Mn NMR has been used as a local probe to study the magnetic properties of this alloy. Rich peak features are observed with the various components assigned to nanoscale F or AF regions. Our results have provided detailed information on the AF regions, which has not been provided by other techniques. Measurements of the temperature dependence of the NMR spectra, in ZF and in a perturbing field were made. The spin-lattice relaxation dependence on T provides detailed information on the nanocluster size distribution and relative concentrations of the F and AF regions. Recently, the Heusler alloy Ni50-xCoxMn40Sn10, with 5 ≤ x ≤ 8, have attracted interest because the low thermal hysteresis and the large change in magnetization which they exhibit at the martensitic transition. Evidence for phase separation of ferromagnetic and antiferromagnetic regions at low temperatures is provided by magnetization and small angle neutron scattering measurements. Superparamagnetism and intrinsic exchange bias effects have been detected below 50 K. Zero field 55Mn NMR has provided detailed information on the nanoscale magnetic properties of samples with x = 7 and, for comparison, x = 14. For x = 7 F and AF regions, with a broad size distribution are identified and our results show that F clusters with the highest blocking temperatures are associated with regions rich in Co ions.

  13. Study of molecular interactions with 13C DNP-NMR.

    Science.gov (United States)

    Lerche, Mathilde H; Meier, Sebastian; Jensen, Pernille R; Baumann, Herbert; Petersen, Bent O; Karlsson, Magnus; Duus, Jens Ø; Ardenkjaer-Larsen, Jan H

    2010-03-01

    NMR spectroscopy is an established, versatile technique for the detection of molecular interactions, even when these interactions are weak. Signal enhancement by several orders of magnitude through dynamic nuclear polarization alleviates several practical limitations of NMR-based interaction studies. This enhanced non-equilibrium polarization contributes sensitivity for the detection of molecular interactions in a single NMR transient. We show that direct (13)C NMR ligand binding studies at natural isotopic abundance of (13)C gets feasible in this way. Resultant screens are easy to interpret and can be performed at (13)C concentrations below muM. In addition to such ligand-detected studies of molecular interaction, ligand binding can be assessed and quantified with enzymatic assays that employ hyperpolarized substrates at varying enzyme inhibitor concentrations. The physical labeling of nuclear spins by hyperpolarization thus provides the opportunity to devise fast novel in vitro experiments with low material requirement and without the need for synthetic modifications of target or ligands.

  14. nmr spectroscopic study and dft calculations of giao nmr shieldings ...

    African Journals Online (AJOL)

    Preferred Customer

    various fields of science and industry such as microelectronic and aerospace ... GIAO/DFT (Gauge Including Atomic Orbitals/Density Functional Theory) approach is .... successfully by using NMR and quantum chemical calculations.

  15. Protein folding on the ribosome studied using NMR spectroscopy

    Science.gov (United States)

    Waudby, Christopher A.; Launay, Hélène; Cabrita, Lisa D.; Christodoulou, John

    2013-01-01

    NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome–nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity. PMID:24083462

  16. NMR studies on UPt 3

    Science.gov (United States)

    Kitaoka, Y.; Tou, H.; Ishida, K.; Kimura, N.; Ōnuki, Y.; Yamamoto, E.; Haga, Y.; Maezawa, K.

    2000-06-01

    A complete set of the 195Pt Knight-shift (KS) data on the superconducting (SC) state in UPt 3 identified the spin structure of the Cooper pair corresponding to the multiple SC phases. UPt 3 was acclaimed as the first odd-parity superconductor including a non-unitary pairing state characterized by the two-component d vector like db+ idc at low T and low H [H. Tou et al., Phys. Rev. Lett. 77 (1996) 1374; 80 (1998) 3129]. We have shed further light on these novel results through a comparison with the singlet even-parity anisotropic superconductors CeCu 2Si 2 and UPd 2Al 3. In the singlet pairing state, the fractional decrease in KS below T c, δK obs is independent of the crystal direction. We have found that δ χobs=( NAμ B/ Ahf)δ Kobs where Ahf is the hyperfine coupling constant, is in good agreement with spin susceptibilities χγel calculated from an enhanced electronic specific heat γel and χnmr from the quasiparticle Korringa relation T1TKs2=const. This gives direct evidence that the χs of heavy quasiparticles in CeCu 2Si 2 and UPd 2Al 3 is rather isotropic and decreases to zero as T→0 due to the Cooper-pair formation. On the other hand in UPt 3, the δ χobsb, cs along the b- and c-axis in the non-unitary-pairing state (B phase) are two orders of magnitude smaller than χγel and χnmr. These anomalously small values for δ χobsb, cs may suggest either that the spin degree of freedom in the B phase is not perfectly locked to the a-axis or that χs is not enhanced although γel is. The latter is theoretically pointed out by Ikeda and Miyake [J. Phys. Soc. Japan 66 (1997) 3714] to be possible if 5f electrons in the non-Kramerse singlet ground state for 5f 2 are hybridized with conduction electrons. We need further effort towards coherent understanding of a microscopic mechanism leading to the occurrence of the odd-parity superconductivity in UPt 3.

  17. Structural Studies of Biological Solids Using NMR

    Science.gov (United States)

    Ramamoorthy, Ayyalusamy

    2011-03-01

    High-resolution structure and dynamics of biological molecules are important in understanding their function. While studies have been successful in solving the structures of water-soluble biomolecules, it has been proven difficult to determine the structures of membrane proteins and fibril systems. Recent studies have shown that solid-state NMR is a promising technique and could be highly valuable in studying such non-crystalline and non-soluble biosystems. I will present strategies to study the structures of such challenging systems and also about the applications of solid-state NMR to study the modes of membrane-peptide interactions for a better assessment of the prospects of antimicrobial peptides as substitutes to antibiotics in the control of human disease. Our studies on the mechanism of membrane disruption by LL-37 (a human antimicrobial peptide), analogs of the naturally occurring antimicrobial peptide magainin2 extracted from the skin of the African frog Xenopus Laevis, and pardaxin will be presented. Solid-state NMR experiments were used to determine the secondary structure, dynamics and topology of these peptides in lipid bilayers. Similarities and difference in the cell-lysing mechanism, and their dependence on the membrane composition, of these peptides will be discussed. Atomic-level resolution NMR structures of amyloidogenic proteins revealing the misfolding pathway and early intermediates that play key roles in amyloid toxicity will also be presented.

  18. Relaxation dispersion NMR spectroscopy for the study of protein allostery.

    Science.gov (United States)

    Farber, Patrick J; Mittermaier, Anthony

    2015-06-01

    Allosteric transmission of information between distant sites in biological macromolecules often involves collective transitions between active and inactive conformations. Nuclear magnetic resonance (NMR) spectroscopy can yield detailed information on these dynamics. In particular, relaxation dispersion techniques provide structural, dynamic, and mechanistic information on conformational transitions occurring on the millisecond to microsecond timescales. In this review, we provide an overview of the theory and analysis of Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion NMR experiments and briefly describe their application to the study of allosteric dynamics in the homeodomain from the PBX transcription factor (PBX-HD). CPMG NMR data show that local folding (helix/coil) transitions in one part of PBX-HD help to communicate information between two distant binding sites. Furthermore, the combination of CPMG and other spin relaxation data show that this region can also undergo local misfolding, reminiscent of conformational ensemble models of allostery.

  19. A multinuclear static NMR study of geopolymerisation

    Energy Technology Data Exchange (ETDEWEB)

    Favier, Aurélie, E-mail: aurelie.favier@epfl.ch [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); Habert, Guillaume [Institute for Construction and Infrastructure Management, ETH Zurich, CH-8093 Zurich (Switzerland); Roussel, Nicolas [Univ Paris-Est, IFSTTAR, Materials Department, 14-20 bd Newton, F-77447 Marne la Vallée Cedex 2 (France); D' Espinose de Lacaillerie, Jean-Baptiste [Ecole Supérieure de Physique et de Chimie Indusrtrielles de la Ville de Paris (ESPCI), ParisTech, PSL Research University, Soft Matter Sciences and Engineering Laboratory SIMM, CNRS UMR 7615, 10 rue Vauquelin, F-75005 Paris (France)

    2015-09-15

    Geopolymers are inorganic binders obtained by alkali activation of aluminosilicates. While the structure of geopolymers is now well understood, the details of the geopolymerisation reaction and their impact on the rheology of the paste remain uncertain. In this work, we follow the elastic properties of a paste made with metakaolin and sodium silicate solution. After the first sharp increase of elastic modulus occurring a few hundred of seconds after mixing and related to the heterogeneous formation of an alumina–silicate gel with a molar ratio Si/Al < 4 located at the grains boundaries, we focus on the progressive increase in elastic modulus on a period of few hours during the setting of the geopolymer. In this study, we combine the study of rheological properties of the paste with {sup 23}Na, {sup 27}Al and {sup 29}Si static NMR measurement in order to better understand the origin of this second increase in elastic modulus. Our results show that, after a few hours, Al and Na evolution in the liquid phase are concomitant. This suggests the precipitation of an aluminosilicate phase where Al is in tetrahedral position and Na compensates the charge. Furthermore, Si speciation confirms this result and allows us to identify the precipitation of a product, which has a chemical composition close to the final composition of geopolymer. This study provides strong evidence for a heterogeneous formation of an aluminosilicate glass directly from the first gel and the silicate solution without the need for a reorganisation of Gel 1 into Gel 2.

  20. Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cancilla, Mark; Lebrilla, Carlito; Ma, Jian-Guo; Medforth, Craig J.; Muzzi, Cinzia M.; Shelnutt, John A.; Smith, Kevin M.; Voss, Lisa

    1999-05-05

    An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) 1H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

  1. An NMR study on shale wettability

    Energy Technology Data Exchange (ETDEWEB)

    Odusina, Elijah; Sondergeld, Carl; Rai, Chandra [University of Oklahoma (United States)

    2011-07-01

    In recent years, the importance of shales as unconventional gas resources has grown significantly. It is therefore important to reach a better understanding of their petrophysical properties. One of the important rock properties that is directly linked to successful hydrocarbon recovery is wettability. This paper presents a study on shale wettability using nuclear magnetic resonance (NMR) to monitor sequential imbibition of brine and oil. Due to the presence of mineralogical variations, low permeability and viscosity, and complex pore structure, the interpretation of wettability using conventional approaches becomes complex. Samples that included 21 core plugs from the Eagle Ford shale, 12 from the Barnett, 11 from the Floyd, and 10 from the Woodford shale were analyzed. The NMR study confirmed the water-wet behavior of Berea sandstone. From the study, it was seen that the Woodford shale showed more affinity for dodecane than did the other shales.

  2. Studies on metabolic regulation using NMR spectroscopy.

    Science.gov (United States)

    Bachelard, H; Badar-Goffer, R; Ben-Yoseph, O; Morris, P; Thatcher, N

    1993-01-01

    The effects of hypoxia and hypoglycaemia on cerebral metabolism and calcium have been studied using multinuclear magnetic resonance spectroscopy. 13C MRS showed that severe hypoxia did not cause any further increase in metabolic flux into lactate seen in mild hypoxia, but there was a further increase in 13C labelling of alanine and glycerol 3-phosphate. These results are discussed in terms of the ability of lactate dehydrogenase to maintain normal levels of NADH in mild hypoxia, but not in severe hypoxia. We conclude that glycerol 3-phosphate and alanine may provide novel means of monitoring severe hypoxia whereas lactate is a reliable indicator only of mild hypoxia. 19F- and 31P NMR spectroscopy showed that neither hypoxia nor hypoglycaemia alone caused any significant change in [Ca2+]i. Combined sequential insults (hypoxia, followed by hypoxia plus hypoglycaemia), or vice versa, produced a 100% increase in [Ca2+]i, whereas immediate exposure to the combined insult (hypoxia plus hypoglycaemia) resulted in a large 5-fold increase in [Ca2+]i, with severe irreversible effects on the energy state. These results are discussed in terms of metabolic adaptation to the single type of insult, which renders the tissue less vulnerable to the combined insult. The effects of this combined insult are far more severe than those caused by glutamate or NMDA, which throws doubt on the current excitoxic hypothesis of cell damage.

  3. The PAW/GIPAW approach for computing NMR parameters: a new dimension added to NMR study of solids.

    Science.gov (United States)

    Charpentier, Thibault

    2011-07-01

    In 2001, Mauri and Pickard introduced the gauge including projected augmented wave (GIPAW) method that enabled for the first time the calculation of all-electron NMR parameters in solids, i.e. accounting for periodic boundary conditions. The GIPAW method roots in the plane wave pseudopotential formalism of the density functional theory (DFT), and avoids the use of the cluster approximation. This method has undoubtedly revitalized the interest in quantum chemical calculations in the solid-state NMR community. It has quickly evolved and improved so that the calculation of the key components of NMR interactions, namely the shielding and electric field gradient tensors, has now become a routine for most of the common nuclei studied in NMR. Availability of reliable implementations in several software packages (CASTEP, Quantum Espresso, PARATEC) make its usage more and more increasingly popular, maybe indispensable in near future for all material NMR studies. The majority of nuclei of the periodic table have already been investigated by GIPAW, and because of its high accuracy it is quickly becoming an essential tool for interpreting and understanding experimental NMR spectra, providing reliable assignments of the observed resonances to crystallographic sites or enabling a priori prediction of NMR data. The continuous increase of computing power makes ever larger (and thus more realistic) systems amenable to first-principles analysis. In the near future perspectives, as the incorporation of dynamical effects and/or disorder are still at their early developments, these areas will certainly be the prime target.

  4. NMR methodologies for studying mitochondrial bioenergetics.

    Science.gov (United States)

    Alves, Tiago C; Jarak, Ivana; Carvalho, Rui A

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is a technique with an increasing importance in the study of metabolic diseases. Its initial important role in the determination of chemical structures (1, 2) has been considerably overcome by its potential for the in vivo study of metabolism (3-5). The main characteristic that makes this technique so attractive is its noninvasiveness. Only nuclei capable of transitioning between energy states, in the presence of an intense and constant magnetic field, are studied. This includes abundant nuclei such as proton ((1)H) and phosphorous ((31)P), as well as stable isotopes such as deuterium ((2)H) and carbon 13 ((13)C). This allows a wide range of applications that vary from the determination of water distribution in tissues (as obtained in a magnetic resonance imaging scan) to the calculation of metabolic fluxes under ex vivo and in vivo conditions without the need to use radioactive tracers or tissue biopsies (as in a magnetic resonance spectroscopy (MRS) scan). In this chapter, some technical aspects of the methodology of an NMR/MRS experiment as well as how it can be used to study mitochondrial bioenergetics are overviewed. Advantages and disadvantages of in vivo MRS versus high-resolution NMR using proton high rotation magic angle spinning (HRMAS) of tissue biopsies and tissue extracts are also discussed.

  5. Sensitivity enhancement and contrasting information provided by free radicals in oriented-sample NMR of bicelle-reconstituted membrane proteins

    Science.gov (United States)

    Tesch, Deanna M.; Nevzorov, Alexander A.

    2014-02-01

    Elucidating structure and topology of membrane proteins (MPs) is essential for unveiling functionality of these important biological constituents. Oriented-sample solid-state NMR (OS-NMR) is capable of providing such information on MPs under nearly physiological conditions. However, two dimensional OS-NMR experiments can take several days to complete due to long longitudinal relaxation times combined with the large number of scans to achieve sufficient signal sensitivity in biological samples. Here, free radicals 5-DOXYL stearic acid, TEMPOL, and CAT-1 were added to uniformly 15N-labeled Pf1 coat protein reconstituted in DMPC/DHPC bicelles, and their effect on the longitudinal relaxation times (T1Z) was investigated. The dramatically shortened T1Z's allowed for the signal gain per unit time to be used for either: (i) up to a threefold reduction of the total experimental time at 99% magnetization recovery or (ii) obtaining up to 74% signal enhancement between the control and radical samples during constant experimental time at “optimal” relaxation delays. In addition, through OS-NMR and high-field EPR studies, free radicals were able to provide positional constraints in the bicelle system, which provide a description of the location of each residue in Pf1 coat protein within the bicellar membranes. This information can be useful in the determination of oligomerization states and immersion depths of larger membrane proteins.

  6. Sensitivity enhancement and contrasting information provided by free radicals in oriented-sample NMR of bicelle-reconstituted membrane proteins.

    Science.gov (United States)

    Tesch, Deanna M; Nevzorov, Alexander A

    2014-02-01

    Elucidating structure and topology of membrane proteins (MPs) is essential for unveiling functionality of these important biological constituents. Oriented-sample solid-state NMR (OS-NMR) is capable of providing such information on MPs under nearly physiological conditions. However, two dimensional OS-NMR experiments can take several days to complete due to long longitudinal relaxation times combined with the large number of scans to achieve sufficient signal sensitivity in biological samples. Here, free radicals 5-DOXYL stearic acid, TEMPOL, and CAT-1 were added to uniformly (15)N-labeled Pf1 coat protein reconstituted in DMPC/DHPC bicelles, and their effect on the longitudinal relaxation times (T1Z) was investigated. The dramatically shortened T1Z's allowed for the signal gain per unit time to be used for either: (i) up to a threefold reduction of the total experimental time at 99% magnetization recovery or (ii) obtaining up to 74% signal enhancement between the control and radical samples during constant experimental time at "optimal" relaxation delays. In addition, through OS-NMR and high-field EPR studies, free radicals were able to provide positional constraints in the bicelle system, which provide a description of the location of each residue in Pf1 coat protein within the bicellar membranes. This information can be useful in the determination of oligomerization states and immersion depths of larger membrane proteins.

  7. MEASURING VARIABILITY SOURCES IN NMR METABOLOMIC STUDIES

    OpenAIRE

    Rozet, Eric; de Tullio, Pascal; Hubert, Philippe; Govaerts., B.

    2013-01-01

    Due to the huge amount of information available in NMR spectra obtained from the analysis of metabolomic experiments, multivariate analysis such as Principal Component Analysis (PCA) are required to understand the influence of treatments over the metabolites [1]. However, many experiments in metabolomics studies have more complexes variability structures than simply comparing several treatments: they may include time effects, biological effects such as diet or hormonal status, and other bloc...

  8. NMR Structural Studies on Alamethicin Dimers

    Institute of Scientific and Technical Information of China (English)

    李星

    2003-01-01

    15N labeled alamethicin dimer was synthesized. The structure and dynamics of alamethicin dimers were studied with nuclear magnetic resonance (NMR) spectroscopy. The data from 15N-labeled alamethicin dimer suggest little differences in conformation between the dimer and monomer in the Aib1-Pro14 region. Significant difference in the conformation of the C-terminus are manifest in the NH chemical shifts in the Val15-Pho20 region.

  9. NMR Studies of Cartilage Dynamics, Diffusion, Degradation

    Science.gov (United States)

    Huster, Daniel; Schiller, Jurgen; Naji, Lama; Kaufmann Jorn; Arnold, Klaus

    An increasing number of people is suffering from rheumatic diseases, and, therefore, methods of early diagnosis of joint degeneration are urgently required. For their establishment, however, an improved knowledge about the molecular organisation of cartilage would be helpful. Cartilage consists of three main components: Water, collagen and chondroitin sulfate (CS) that is (together with further polysaccharides and proteins) a major constituent of the proteoglycans of cartilage. 1H and 13C MAS (magic-angle spinning) NMR (nuclear magnetic resonance) opened new perspectives for the study of the macromolecular components in cartilage. We have primarily studied the mobilities of CS and collagen in bovine nasal and pig articular cartilage (that differ significantly in their collagen/polysaccharide content) by measuring 13C NMR relaxation times as well as the corresponding 13C CP (cross polarisation) MAS NMR spectra. These data clearly indicate that the mobility of cartilage macromolecules is broadly distributed from almost completely rigid (collagen) to highly mobile (polysaccharides), which lends cartilage its mechanical strength and shock-absorbing properties.

  10. Polymeric proanthocyanidins 13C NMR studies of procyanidins

    Science.gov (United States)

    Lawrence J. Porter; Roger H. Newman; Lai Yeap Foo; Herbert Wong; Richard W. Hemingway

    1982-01-01

    Proanthocyanidin polymers have been shown to consist entirely of flavan-3-ol units by a combination of techniques including 13C n.m.r. spectroscopy. The 13C n.m.r. spectra of the polymers and related molecules are now considered in more detail. Prior to this study UC n.m.r. data has been published of procyanidins and...

  11. Studies of Transition Metal Complexes Using Dynamic NMR Techniques.

    Science.gov (United States)

    Coston, Timothy Peter John

    Available from UMI in association with The British Library. This Thesis is primarily concerned with the quantitative study of fluxional processes in, predominantly platinum(IV) complexes, with the ligands 1,1,2,2-tetrakis(methylthio)ethane (MeS)_2CHCH(SMe)_2 , and 1,1,2,2-tetrakis(methylthio)ethene (MeS) _2C=C(SMe)_2. Quantitative information relating to the energetics of these processes has been obtained by a combination of one- and two-dimensional NMR techniques. Chapter One provides an introduction to the background of fluxional processes in transition metal complexes together with data concerning the energetics of the processes that have already been studied by NMR techniques. Chapter Two provides a thorough grounding in NMR techniques, in particular those concerned with the quantitative measurement of rates involved in chemical exchange processes. A description of the use of 2D EXSY NMR spectroscopy in obtaining rate data is given. The properties of the magnetic isotope of platinum are given in Chapter Three. A general survey is also given of some additional compounds that have already been studied by platinum-195 spectroscopy. Chapter Four is concerned with the quantitative study of low temperature (complexes (PtXMe_3 (MeS)_2CHCH(SMe) _2) (X = Cl, Br, I). These complexes were studied by dynamic nuclear magnetic resonance and the information regarding the rates of sulphur inversion was obtained by complete band-shape analysis. Chapter Five is concerned with high temperature (>333 K) fluxionality, of the previous complexes, as studied by a combination of one- and two -dimensional NMR techniques. Aside from obtaining thermodynamic parameters for all the processes, a new novel mechanism is proposed. Chapter Six is primarily concerned with the NMR investigation of the new dinuclear complexes ((PtXMe _3)_2(MeS) _2CHCH(SMe)_2) (X = Cl, Br, I). The solution properties have been established and thermo-dynamic parameters obtained for low and high temperature

  12. Study of NMR porosity for terrestrial formation in China

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaowen; XIAO Lizhi; XIE Ranhong; ZHANG Yuanzhong

    2006-01-01

    NMR logging is an effective method for porosity measurement. NMR-derived porosity only comes from the pore fluid and is, in principle, not affected by rock matrix. However, it is found that the difference between NMR-derived and conventional log-derived porosities is often between 2 to 6 pu, which is unacceptable, in terrestrial formation in China. In the paper, the theory of NMR porosity was reviewed. The influence factors on NMR porosity error were analyzed based on NMR core measurements. More than 30 core samples with a wide range of porosities including sandstone, limestone and artificial ceramic were chosen for the conventional and NMR porosity measurements. The current NMR data acquisition method was studied based on laboratory NMR core measurements and found to be not good for terrestrial formation. A new NMR data acquisition method suiting for terrestrial formation in China was proposed and much improved the accuracy of NMR porosity measurement. It is suggested that the analysis of core samples from different regions should be carried out before logging in order to obtain accurate NMR porosity.

  13. Studies on supramolecular gel formation using DOSY NMR.

    Science.gov (United States)

    Nonappa; Šaman, David; Kolehmainen, Erkki

    2015-04-01

    Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential DOSY processing, and the results were compared with the automated Bayesian DOSY transformation to obtain 2D plots. Our results provide useful information on the stepwise self-assembly of small molecules leading to gelation. We believe that the results obtained from these experiments are applicable in determining the CGC and gel melting temperatures of supramolecular gels.

  14. NMR spectroscopy applied to the eye: Drugs and metabolic studies

    Energy Technology Data Exchange (ETDEWEB)

    Saether, Oddbjoern

    2005-07-01

    NMR spectroscopy has been extensively applied in biomedical research during the last decades. It has proved to be an analytical tool of great value. From being mainly used in chemistry, technological developments have expanded the application of NMR spectroscopy to a great wealth of disciplines. With this method, biochemical information can be obtained by analysing tissue extracts. Moreover, NMR spectroscopy is increasingly employed for pharmacokinetic studies and analysis of biofluids. Technological progress has provided increased sensitivity and resolution in the spectra, which enable even more of the complexity of biological samples to be elucidated. With the implementation of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy in biomedicine, intact tissue samples or biopsies can be investigated. Thus, NMR spectroscopy has an ever-increasing impact in metabolic screening of human samples and in animal models, and methods are also increasingly realised in vivo. The present work, NMR spectroscopy applied to eye research, consists of two main parts. Firstly, the feasibility to monitor fluorinated ophthalmic drugs directly in the eye was assessed. Secondly, HR-MAS H1 NMR spectroscopy was applied for metabolic profiling of the anterior eye segment, specifically to analyse metabolic changes in intact corneal and lenticular samples after cataractogenic insults. This work included metabonomics with the application of pattern recognition methods to analyse HR-MAS spectra of eye tissues. Optimisation strategies were explored for F19 NMR detection of fluorinated drugs in a phantom eye. S/N gains in F19 NMR spectroscopy were achieved by implementing time-share H1 decoupling at 2.35 T. The method is advantageous for compounds displaying broad spectral coupling patterns, though detection of drugs at concentrations encountered in the anterior eye segment after topical application was not feasible. Higher magnetic fields and technological improvements could enable

  15. An NMR study of adsorbed helium films

    Science.gov (United States)

    Kent, Anthony Joseph

    The properties of sub-monolayer Helium-3 films adsorbed on two totally different but planar substrates, Mylar† film and exfoliated graphite have been studied using NMR. The nuclear magnetic relaxation times T1 and T 2 have been measured as functions of fractional monolayer completion, temperature, substrate plane orientation and Larmor frequency using a specially designed and constructed NMR spectrometer system. The results obtained with a Mylar film substrate are consistent3with the formation of patches of solid 3He at regions of preferential adsorption on the substrate. Measurements of T2 m very low coverage 3He films on exfoliated graphite also indicate that the adsorbate forms areas of relatively high density solid, in agreement with the thermodynamic analysis of Elgin and Goodstein. Finally, detailed measurements of T2 as a function of all of the above parameters at low areal densities will help us to characterise the relaxation processes for the fluid phase of 33He on exfoliated graphite. †Mylar is the tradename of poly(ethelene-terephthalate) film, marketed by Du Pont.

  16. Solid state NMR study of bone mineral

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.

    1992-01-01

    In high field (9.4 T) CP MASS (cross polarization magic angle sample spinning) studies, in contrast to the scheme in the literature that infers the presence of minor constituents in spectra, we developed a new scheme to suppress the main part of the spectra to show the minor constituents. In order to perform in vivo solid state NMR studies, a double tuned two port surface coil probe was constructed. This probe is a modified version of the traditional Cross probe, which utilizes two 1/4 wave length 50 ohm transmission line, one with open ended and the other with shorted end, to isolate the high and low frequency circuits. The two resonance frequencies in Cross probe were proton and carbon. Our probe is designed to resonate at the proton and phosphorus frequencies, which are much closer to each other and hence more difficult to be tuned and matched simultaneously. Our approach to solve this problem is that instead of using standard 50 ohm transmission lines, we constructed a low capacity open end coaxial transmission line and low inductance shorted end coaxial transmission line. The Q of the phosphorus channel is high. We developed a short contact time cross polarization technique for non-MASS spectroscopy which reduces the signal of the major component of bone mineral to emphasize the minor component. By applying this technique on intact pork bone samples with our home made surface coil, we observed the wide line component, acid phosphate, for the first time. Hydroxyapatite, brushite and octacalcium are considered in the literature to be the model compounds for bone mineral. Cross polarization dynamics has been studied on hydroxyapatite and brushite, which yielded an NMR value for the distance between proton and phosphorus. One and two dimensional CP MASS spectroscopy of octacalcium phosphate were also studied, which revealed the different cross polarization rates and anisotropic channel shifts of acid phosphate and phosphate ions in octacalcium phosphate.

  17. NMR studies of polysaccharides from brown seaweeds

    Energy Technology Data Exchange (ETDEWEB)

    Noseda, M.D.; Tisher, C.A.; Gorin, P.A.J.; Duarte, M.E.R. [Parana Univ., Curitiba, PR (Brazil). Dept. de Bioquimica; Cerezo, A.S. [Buenos Aires Univ. Nacional (Argentina). Dept. de Quimica Organica

    1997-12-31

    Alginic acid is the major intercellular polysaccharide serving as matrix in the brown algae and is comprised of an unbranched chain of (1->4)-linked {beta}-D-mannuronic acid (M) and {alpha}-L-guluronic acid (G), arranged in a blockwise fashion. The composition of the monomer residues and the block structure varies depending on the source of the polymer. The selective binding of cations to alginate accounts for its ability to form gels, which is dependent on the number and lenght of the G-blocks. They are widely used industrially for their ability to retain water, and for their gelling, viscosifying and stabilizing properties (Smidsrod and draget, 1996). In this study, alginate composition and block structure in Sargassum stenophyllum has been determined by chemical methods and NMR spectroscopic analysis. (author) 4 refs., 3 figs.

  18. Isotope labeling for NMR studies of macromolecular structure and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Wright, P.E. [Scripps Research Institute, La Jolla, CA (United States)

    1994-12-01

    Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform {sup 13}C, {sup 15}N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific {sup 13}C and {sup 15}N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions.

  19. Studies on irradiation stability of polystyrene by NMR

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; SUN Wan-Fu; XIE Cheng-Xi

    2004-01-01

    The irradiation stability of polystyrene (PS) was studied by 13C and 1H NMR spectra, Nuclear Overhauser Relaxation (NOE) and 13C NMR spin-lattice relaxation time (T1). The results indicate that 13C and 1H NMR chemical shifts, NOE and T1 were almost invariant with the increase of irradiation dose. This shows that polystyrene is particularly stable within 2.5 kGy doses and the mechanism of its stability is discussed.

  20. NMR-Metabolic Methodology in the Study of GM Foods

    Science.gov (United States)

    The 1H NMR methodology used in the study of genetically modified (GM) foodstuff is discussed. The study of transgenic lettuce (Lactuca sativa cv "Luxor") over-expressing the KNAT1 gene from Arabidopsis is presented as a novel study-case. The 1H NMR metabolic profiling was carried out. Twenty-two wat...

  1. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang; Feng; Wu; Chengtai; 等

    2003-01-01

    The NMR methods (including 1H NMR, variable temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  2. NMR Study of Hydroxyl-Substituted Macrocyclic Hexaamine in Solution

    Institute of Scientific and Technical Information of China (English)

    Liang Feng; Wu Xiao-jun; Wu Cheng-tai

    2003-01-01

    The NMR methods (including 1H NMR, vari-able temperature method and the 2D COSY technique) were employed to study the conformation of 3,13-dihydroxyl-1,5,8,11,15,18-hexaazacyclicamine hexahydrobromide in aqueous solution. It was found that the ring is flexible.

  3. NMR potentials for studying physical processes in fossil coals

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, Anatolii D; Ul' yanova, Ekaterina V; Vasilenko, Tat' yana A [Institute of Mining Processes Physics, National Academy of Sciences of Ukraine, Donetsk (Ukraine)

    2005-11-30

    High-resolution, pulsed, and wide-line NMR studies of fossil coals are reviewed. Coal substance conversion due to outbursts is discussed. Results on water and methane interactions with coal substance, which provide insight into the dynamic characteristics of boundary water, the location of methane in coal structure, and water and methane's hazard implications for coal beds (gas- or geodynamic phenomena) are presented; these are shown to have potential for predicting and preventing life threatening situations. (instruments and methods of investigation)

  4. NMR system and method having a permanent magnet providing a rotating magnetic field

    Science.gov (United States)

    Schlueter, Ross D [Berkeley, CA; Budinger, Thomas F [Berkeley, CA

    2009-05-19

    Disclosed herein are systems and methods for generating a rotating magnetic field. The rotating magnetic field can be used to obtain rotating-field NMR spectra, such as magic angle spinning spectra, without having to physically rotate the sample. This result allows magic angle spinning NMR to be conducted on biological samples such as live animals, including humans.

  5. NMR studies of the conformation and motion of tetrahydrofuran in graphite intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, D. F. [Lawrence Berkeley Lab., CA (United States); California Univ., Berkeley, CA (United States). Dept. of Chemistry

    1991-11-01

    The behavior of tetrahydrofuran (THF) molecules intercalated in graphite layers in compounds Cs(THF){sub 1.3}C{sub 24} and K(THF){sub 2.5}C{sub 24} was studied by proton NMR. The graphite layers in these compounds impose a uniform ordering on the THF molecules, giving rise to sharp NMR spectra. Experimental and simulated proton NMR spectra were used to investigate geometry, orientation and conformation of intercalated THF, and to determine whether pseudorotation, a large amplitude low-frequency vibration observed in gaseous THF, can also occur in the constrained environment provided by the graphite intercalation compounds. Deuterium and multiple quantum proton NMR spectra were also simulated in order to determine if these techniques could further refine the proton NMR results.

  6. Solid state NMR studies of gels derived from low molecular mass gelators.

    Science.gov (United States)

    Nonappa; Kolehmainen, E

    2016-07-13

    Since its invention more than six decades ago, nuclear magnetic resonance (NMR) spectroscopy has evolved as an inevitable part of chemical as well as structural analysis of small molecules, polymers, biomaterials and hybrid materials. In the solution state, due to the increased viscosity of complex viscoelastic fluids such as gels, liquid crystals and other soft materials, the rate of molecular tumbling is reduced, which in turn affects the chemical shift anisotropy, dipolar and quadrupolar interactions. As a consequence the solution state NMR spectra show broad lines, and therefore, extracting detailed structural information is a challenging task. In this context, solid state (SS) NMR has the ability to distinguish between a minute amount of polymorphic forms, conformational changes, and the number of non-equivalent molecules in an asymmetric unit of a crystal lattice, and to provide both qualitative as well as quantitative analytical data with a short-range order. Therefore, SS NMR has continued to evolve as an indispensable tool for structural analysis and gave birth to a new field called NMR crystallography. Solid state cross polarization (CP) and high resolution (HR) magic angle spinning (MAS) NMR spectroscopy has been used to study weak interactions in polymer gels. However, the application of SS NMR spectroscopy to study gels derived from low molecular weight gelators has been limited until recently. In this review, we will focus on the importance of solid state NMR spectroscopy in understanding and elucidating the structure of supramolecular gels derived from low molecular weight gelators with selected examples.

  7. Solid state NMR studies of gels derived from low molecular mass gelators

    Science.gov (United States)

    Kolehmainen, E.

    2016-01-01

    Since its invention more than six decades ago, nuclear magnetic resonance (NMR) spectroscopy has evolved as an inevitable part of chemical as well as structural analysis of small molecules, polymers, biomaterials and hybrid materials. In the solution state, due to the increased viscosity of complex viscoelastic fluids such as gels, liquid crystals and other soft materials, the rate of molecular tumbling is reduced, which in turn affects the chemical shift anisotropy, dipolar and quadrupolar interactions. As a consequence the solution state NMR spectra show broad lines, and therefore, extracting detailed structural information is a challenging task. In this context, solid state (SS) NMR has the ability to distinguish between a minute amount of polymorphic forms, conformational changes, and the number of non-equivalent molecules in an asymmetric unit of a crystal lattice, and to provide both qualitative as well as quantitative analytical data with a short-range order. Therefore, SS NMR has continued to evolve as an indispensable tool for structural analysis and gave birth to a new field called NMR crystallography. Solid state cross polarization (CP) and high resolution (HR) magic angle spinning (MAS) NMR spectroscopy has been used to study weak interactions in polymer gels. However, the application of SS NMR spectroscopy to study gels derived from low molecular weight gelators has been limited until recently. In this review, we will focus on the importance of solid state NMR spectroscopy in understanding and elucidating the structure of supramolecular gels derived from low molecular weight gelators with selected examples. PMID:27374054

  8. Proton NMR studies on Megaphaera elsdenii flavodoxin : structure elucidation by 2D-NMR and implications

    NARCIS (Netherlands)

    Mierlo, van C.

    1990-01-01

    1H NMR techniques have been applied for a thorough study of the uncrystallizable Megasphaera elsdenii flavodoxin in its three redox states. The aim of the research project described in this thesis was to obtain answers regarding questions concerni

  9. NMR contributions to structural dynamics studies of intrinsically disordered proteins☆

    Science.gov (United States)

    Konrat, Robert

    2014-01-01

    Intrinsically disordered proteins (IDPs) are characterized by substantial conformational plasticity. Given their inherent structural flexibility X-ray crystallography is not applicable to study these proteins. In contrast, NMR spectroscopy offers unique opportunities for structural and dynamic studies of IDPs. The past two decades have witnessed significant development of NMR spectroscopy that couples advances in spin physics and chemistry with a broad range of applications. This article will summarize key advances in basic physical-chemistry and NMR methodology, outline their limitations and envision future R&D directions. PMID:24656082

  10. Some nitrogen-14 NMR studies in solids

    Energy Technology Data Exchange (ETDEWEB)

    Pratum, T.K.

    1983-11-01

    The first order quadrupolar perturbation of the /sup 14/N NMR spectrum yields information regarding the static and dynamic properties of the surrounding electronic environment. Signal to noise problems caused by long /sup 14/N longitudinal relaxation times (T/sub 1/) and small equilibrium polarizations are reduced by rotating frame cross polarization (CP) experiments between /sup 14/N and /sup 1/H. Using quadrupolar echo and CP techniques, the /sup 14/N quadrupolar coupling constants (e/sup 2/qQ/h) and asymmetry parameters (eta) have been obtained for a variety of tetraalkylammonium compounds by observation of their quadrupolar powder patterns at various temperatures. For choline chloride and iodide the /sup 14/N NMR powder patterns exhibit the effects of anisotropic molecular motion, while choline bromide spectra show no such effects.

  11. NMR studies of nucleic acid dynamics

    Science.gov (United States)

    Al-Hashimi, Hashim M.

    2013-12-01

    Nucleic acid structures have to satisfy two diametrically opposite requirements; on one hand they have to adopt well-defined 3D structures that can be specifically recognized by proteins; on the other hand, their structures must be sufficiently flexible to undergo very large conformational changes that are required during key biochemical processes, including replication, transcription, and translation. How do nucleic acids introduce flexibility into their 3D structure without losing biological specificity? Here, I describe the development and application of NMR spectroscopic techniques in my laboratory for characterizing the dynamic properties of nucleic acids that tightly integrate a broad set of NMR measurements, including residual dipolar couplings, spin relaxation, and relaxation dispersion with sample engineering and computational approaches. This approach allowed us to obtain fundamental new insights into directional flexibility in nucleic acids that enable their structures to change in a very specific functional manner.

  12. EXPERIMENTAL AND THEORETICAL NMR STUDY OF 4-(1 ...

    African Journals Online (AJOL)

    Preferred Customer

    3 Department of Physics, Arts and Science Faculty, Dumlupınar University, Kütahya, Turkey. 4 Department ... been studied experimentally and theoretically using nuclear magnetic resonance (NMR) spectroscopy. 1H, 13C, ... INTRODUCTION.

  13. NMR studies on polyphosphide Ce6Ni6P17

    Science.gov (United States)

    Koyama, T.; Yamada, H.; Ueda, K.; Mito, T.; Aoyama, Y.; Nakano, T.; Takeda, N.

    2016-02-01

    We report the result of 31P nuclear magnetic resonance (NMR) studies on Ce6Ni6P17. The observed NMR spectra show a Lorentzian-type and an asymmetric shapes, reflecting the local symmetry around each P site in the cubic unit cell. We have identified the observed NMR lines corresponding to three inequivalent P sites and deduced the temperature dependence of the Knight shift for each site. The Knight shifts increase with decreasing temperature down to 1.5 K, indicating a localized spin system of Ce6Ni6P17. Antiferromagnetic correlation between 4f spins is suggested from the negative sign of the Weiss-temperature.

  14. 31P NMR Study on Some Phosphorus-Containing Compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    31P NMR has become a widely applied spectroscopic probe of the structure of phosphorus-containing compounds. Meanwhile, the application of 31P NMR has been rapidly expanded to biochemistry and medicinal chemistry of phosphorus-containing compounds because the growing importance of the phosphorus compounds is now widely realized. We report here the results of 31P NMR study on some phosphorus-containing compounds, namely, O-alkyl O-4-nitrophenyl methyl phosphonates with different alkyl chain-length (MePO-n), 4-nitrophenyl alkylphenylphosphinates with different alkyl chain-length (PhP-n), diethyl phosphono- acetonitrile anion and diethyl phosphite anion . Our results indicate that 31P NMR can not only be applied to not only the study of the hydrolytic reactions of MePO-8 and PhP-8 but also be applied to the study of the presence of the anions of diethylphosphonoacetonitrile and diethyl phosphite in nucleophilic reactions.

  15. Interfaces in polymer nanocomposites – An NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Böhme, Ute; Scheler, Ulrich, E-mail: scheler@ipfdd.de [Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden (Germany)

    2016-03-09

    Nuclear Magnetic Resonance (NMR) is applied for the investigation of polymer nanocomposites. Solid-state NMR is applied to study the modification steps to compatibilize layered double hydroxides with non-polar polymers. {sup 1}H relaxation NMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the transverse relaxation time T{sub 2} is most suited. In this presentation we report on two applications of T{sub 2} measurements under external mechanical stress. In a low-field system relaxation NMR studies are performed in-situ under uniaxial stress. High-temperature experiments in a Couette cell permit the investigation of the polymer dynamics in the melt under shear flow.

  16. NMR study of small molecule adsorption in MOF-74-Mg.

    Science.gov (United States)

    Lopez, M G; Canepa, Pieremanuele; Thonhauser, T

    2013-04-21

    We calculate the carbon nuclear magnetic resonance (NMR) shielding for CO2 and the hydrogen shieldings for both H2 and H2O inside the metal organic framework MOF-74-Mg. Our ab initio calculations are at the density functional theory level using the van der Waals including density functional vdW-DF. The shieldings are obtained while placing the small molecules throughout the structure, including the calculated adsorption site for various loading scenarios. We then explore relationships between loading, rotational and positional characteristics, and the NMR shieldings for each adsorbate. Our NMR calculations show a change in the shielding depending on adsorbate, position, and loading in a range that is experimentally observable. We further provide a simple model for the energy and the NMR shieldings throughout the cavity of the MOF. By providing this mapping of shielding to position and loading for these adsorbates, we argue that NMR probes could be used to provide additional information about the position at which these small molecules bind within the MOF, as well as the loading of the adsorbed molecule.

  17. NMR study of small molecule adsorption in MOF-74-Mg

    Science.gov (United States)

    Lopez, M. G.; Canepa, Pieremanuele; Thonhauser, T.

    2013-04-01

    We calculate the carbon nuclear magnetic resonance (NMR) shielding for CO2 and the hydrogen shieldings for both H2 and H2O inside the metal organic framework MOF-74-Mg. Our ab initio calculations are at the density functional theory level using the van der Waals including density functional vdW-DF. The shieldings are obtained while placing the small molecules throughout the structure, including the calculated adsorption site for various loading scenarios. We then explore relationships between loading, rotational and positional characteristics, and the NMR shieldings for each adsorbate. Our NMR calculations show a change in the shielding depending on adsorbate, position, and loading in a range that is experimentally observable. We further provide a simple model for the energy and the NMR shieldings throughout the cavity of the MOF. By providing this mapping of shielding to position and loading for these adsorbates, we argue that NMR probes could be used to provide additional information about the position at which these small molecules bind within the MOF, as well as the loading of the adsorbed molecule.

  18. Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

    Science.gov (United States)

    Kupka, Teobald; Wieczorek, Piotr P.

    2016-01-01

    In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of 1H and 13C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.

  19. Solid state NMR study calcium phosphate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, J.L.; Facchini, L.; Legrand, A.P. (Laboratoire de Physique Quantique, Paris (France). CNRS, URA421, ESPCI); Rey, C. (CNRS, Toulouse (France). ENSC. Laboratoire de Physico-chimie des Solides); Lemaitre, J. (EPF Lausanne (France). Laboratoire de Technologie des Poudres)

    1990-04-01

    High-resolution {sup 31}P and {sup 1}H NMR spectra at 40 and 121 MHz {sup 31}P and 300 MHz {sup 1}H of synthetic and biological samples of calcium phosphates have been obtained by magic angle spinning (MAS) at spinning speeds up to 6.5 kHz, and high power proton decoupling. The samples include crystalline hydroxyapatite, a deficient hydroxyapatite characterized by a Ca/P atomic ratio of 1.5, a poorly crystallized hydroxyapatite, monetite, brushite, octacalcium phosphate, {beta}-tricalcium phosphate and rabbit femoral bone. The interactions between nuclei in unlike structures and the mobility of acid protons are discussed. (author). 11 refs.; 2 figs.; 1 tab.

  20. Fresco paintings studied by unilateral NMR

    Science.gov (United States)

    Proietti, N.; Capitani, D.; Lamanna, R.; Presciutti, F.; Rossi, E.; Segre, A. L.

    2005-11-01

    Unilateral NMR has been used to monitor the state of conservation of frescoes in the Vasari's house in Florence. The causes of deterioration of ancient frescoes are varied, which result in the detachment and crumbling of the painted film from the supporting plaster and in the outcropping of salts. Unilateral measurements of Hahn echo performed on such frescoes have allowed a perfect identification of the detachment of the painted film from the plaster. The presence of soluble salts on the pictorial film affects the spin-spin relaxation times, T2. It is then possible using this technique, to characterize the effect of chemical treatments, of cleansing and consolidation procedures using the distribution of T2 spin-spin relaxation times.

  1. 31P NMR for the study of P metabolism and translocation in arbuscular mycorrhizal fungi

    DEFF Research Database (Denmark)

    Rasmussen, N.; Lloyd, D.C.; Ratcliffe, R.G.

    2000-01-01

    P-31 nuclear magnetic resonance (NMR) spectroscopy was used to study phosphate (P) metabolism in mycorrhizal and nonmycorrhizal roots of cucumber (Cucumis sativus L) and in external mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith. The in vivo NMR method allows...... biological systems to be studied non-invasively and non-destructively. (3)1P NMR experiments provide information about cytoplasmic and vacuolar pH, based on the pH-dependent chemical shifts of the signals arising from the inorganic P (P-i) located in the two compartments. Similarly, the resonances arising...... from alpha, beta and gamma phosphates of nucleoside triphosphates (NTP) and nucleoside diphosphates (NDP) supply knowledge about the metabolic activity and the energetic status of the tissue. In addition, the kinetic behaviour of P uptake and storage can be determined with this method. The (3)1P NMR...

  2. NMR structural studies of protein-small molecule interactions

    NARCIS (Netherlands)

    Shah, Dipen M.

    2014-01-01

    The research presented in the thesis describes the development and implementation of solution based NMR methods that provide 3D structural information on the protein-small molecule complexes. These methods can be critical for structure based drug design and can be readily applied in the early stages

  3. NMR Studies of Some Plasma Proteins.

    Science.gov (United States)

    Lawrence, Mark P.

    Available from UMI in association with The British Library. Requires signed TDF. The work reported in this thesis consists of a study of the solution structure of a domain of protein structure found in some of the enzymes involved in blood coagulation. These domains, known as kringles, are of between 78 and 82 residues and contain three conserved disulphide bridges in their primary sequence. The study attempts to elucidate the nature of the lysine-binding site of the fourth kringle of human plasminogen to probe its physiological action, and a theory is developed to explain the overall fold of the protein in terms of its physiological role. The protein structure is found to contain only one small region of secondary structure, an antiparallel beta-sheet of about 8 residues, which provides the support for the binding site. The binding site itself consists of a hydrophobic channel provided by the aromatic residues at positions 61, 63, 71 and 73 in the beta-sheet and a negatively charged site at one end of this channel provided by the aspartic acid residues at positions 54 and 56. The beta-sheet appears to become more tightly defined on binding the kringle with alpha,omega -amino acids which are analogues of lysine and exhibit known anti-fibrinolytic properties. The rest of the solution structure appears to be less clearly defined and relies mainly on the three disulphide bridges and some rather isolated hydrogen bonding for maintenance of the fold. An explanation for this structure with a rigid binding site and a more flexible region for the remainder of the domain is proposed. Shorter studies are reported on the second kringle of bovine prothrombin and the first of human plasminogen which suggest strongly that the kringle fold is conserved.

  4. NMR-Metabolic Methodology in the Study of GM Foods

    Directory of Open Access Journals (Sweden)

    Irene D’Amico

    2010-01-01

    Full Text Available The 1H-NMR methodology used in the study of genetically modified (GM foods is discussed. Transgenic lettuce (Lactuca sativa cv "Luxor" over-expressing the Arabidopsis KNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars present in leaves of conventional and GM lettuce were monitored by NMR and quantified at two developmental stages. The NMR spectra did not reveal any difference in metabolite composition between the GM lettuce and the wild type counterpart. Statistical analyses of metabolite variables highlighted metabolism variation as a function of leaf development as well as the transgene. A main effect of the transgene was in altering sugar metabolism.

  5. Some specific features of the NMR study of fluid flows

    Science.gov (United States)

    Davydov, V. V.

    2016-07-01

    Some specific features of studying fluid flows with a NMR spectrometer are considered. The consideration of these features in the NMR spectrometer design makes it possible to determine the relative concentrations of paramagnetic ions and measure the longitudinal and transverse relaxation times ( T 1 and T 2, respectively) in fluid flows with an error no larger than 0.5%. This approach allows one to completely avoid errors in determining the state of a fluid from measured relaxation constants T 1 and T 2, which is especially urgent when working with medical suspensions and biological solutions. The results of an experimental study of fluid flows are presented.

  6. Informing saccharide structural NMR studies with density functional theory calculations.

    Science.gov (United States)

    Klepach, Thomas; Zhao, Hongqiu; Hu, Xiaosong; Zhang, Wenhui; Stenutz, Roland; Hadad, Matthew J; Carmichael, Ian; Serianni, Anthony S

    2015-01-01

    Density functional theory (DFT) is a powerful computational tool to enable structural interpretations of NMR spin-spin coupling constants ( J-couplings) in saccharides, including the abundant (1)H-(1)H ( JHH), (13)C-(1)H ( JCH), and (13)C-(13)C ( JCC) values that exist for coupling pathways comprised of 1-4 bonds. The multiple hydroxyl groups in saccharides, with their attendant lone-pair orbitals, exert significant effects on J-couplings that can be difficult to decipher and quantify without input from theory. Oxygen substituent effects are configurational and conformational in origin (e.g., axial/equatorial orientation of an OH group in an aldopyranosyl ring; C-O bond conformation involving an exocyclic OH group). DFT studies shed light on these effects, and if conducted properly, yield quantitative relationships between a specific J-coupling and one or more conformational elements in the target molecule. These relationships assist studies of saccharide structure and conformation in solution, which are often challenged by the presence of conformational averaging. Redundant J-couplings, defined as an ensemble of J-couplings sensitive to the same conformational element, are particularly helpful when the element is flexible in solution (i.e., samples multiple conformational states on the NMR time scale), provided that algorithms are available to convert redundant J-values into meaningful conformational models. If the latter conversion is achievable, the data can serve as a means of testing, validating, and refining theoretical methods like molecular dynamics (MD) simulations, which are currently relied upon heavily to assign conformational models of saccharides in solution despite a paucity of experimental data needed to independently validate the method.

  7. Biomolecular recognition mechanisms studied by NMR spectroscopy and MD simulations

    NARCIS (Netherlands)

    Hsu, Shang-Te Danny

    2004-01-01

    This thesis describes the use of solution Nuclear Magnetic Resonance (NMR) spectroscopy and Molecular Dynamics (MD) simulations to study the mechanism of biomolecular recognition with two model systems: i) lipid II-binding lantibiotics (lanthionine-containing antibiotics) and ii) the human immunodef

  8. Solid State NMR Studies of Energy Conversion and Storage Materials

    Science.gov (United States)

    Jankuru Hennadige, Sohan Roshel De Silva

    NMR (Nuclear magnetic resonance) spectroscopy is utilized to study energy conversion and storage materials. Different types of NMR techniques including Magic Angle Spinning, Cross-polarization and relaxation measurement experiments were employed. Four different projects are discussed in this dissertation. First, three types of CFx battery materials were investigated. Electrochemical studies have demonstrated different electrochemical performances by one type, delivering superior performance over the other two. 13C and 19F MAS NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among different types. Next as the second project, layered polymer dielectrics were investigated by NMR. Previous studies have shown that thin film capacitors are improved by using alternate layers of two polymers with complementary properties: one with a high breakdown strength and one with high dielectric constant as opposed to monolithic layers. 13C to 1H cross-polarization techniques were used to investigate any inter-layer properties that may cause the increase in the dielectric strength. The third project was to study two types of thermoelectric materials. These samples were made of heavily doped phosphorous and boron in silicon by two different methods: ball-milled and annealed. These samples were investigated by NMR to determine the degree of disorder and obtain insight into the doping efficiency. The last ongoing project is on a lithium-ion battery system. The nature of passivating layers or the solid electrolyte interphase (SEI) formed on the electrodes surface is important because of the direct correlation between the SEI and the battery life time/durability. Multinuclear (7Li, 19F, 31P) techniques are employed to identify the composition of the SEI formation of both positive and negative electrodes.

  9. Solution NMR Studies of Mycobacterium tuberculosis Proteins for Antibiotic Target Discovery

    Directory of Open Access Journals (Sweden)

    Do-Hee Kim

    2017-08-01

    Full Text Available Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, which triggers severe pulmonary diseases. Recently, multidrug/extensively drug-resistant tuberculosis strains have emerged and continue to threaten global health. Because of the development of drug-resistant tuberculosis, there is an urgent need for novel antibiotics to treat these drug-resistant bacteria. In light of the clinical importance of M. tuberculosis, 2067 structures of M. tuberculsosis proteins have been determined. Among them, 52 structures have been solved and studied using solution nuclear magnetic resonance (NMR. The functional details based on structural analysis of M. tuberculosis using NMR can provide essential biochemical data for the development of novel antibiotic drugs. In this review, we introduce diverse structural and biochemical studies on M. tuberculosis proteins determined using NMR spectroscopy.

  10. An NMR Study of Enzyme Activity.

    Science.gov (United States)

    Peterman, Keith E.; And Others

    1989-01-01

    A laboratory experiment designed as a model for studying enzyme activity with a basic spectrometer is presented. Included are background information, experimental procedures, and a discussion of probable results. Stressed is the value of the use of Nuclear Magnetic Resonance in biochemistry. (CW)

  11. An NMR Study of Enzyme Activity.

    Science.gov (United States)

    Peterman, Keith E.; And Others

    1989-01-01

    A laboratory experiment designed as a model for studying enzyme activity with a basic spectrometer is presented. Included are background information, experimental procedures, and a discussion of probable results. Stressed is the value of the use of Nuclear Magnetic Resonance in biochemistry. (CW)

  12. Diffusion NMR methods applied to xenon gas for materials study

    Science.gov (United States)

    Mair, R. W.; Rosen, M. S.; Wang, R.; Cory, D. G.; Walsworth, R. L.

    2002-01-01

    We report initial NMR studies of (i) xenon gas diffusion in model heterogeneous porous media and (ii) continuous flow laser-polarized xenon gas. Both areas utilize the pulsed gradient spin-echo (PGSE) techniques in the gas phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients--a brief overview of this area is provided in the Introduction. The heterogeneous or multiple-length scale model porous media consisted of random packs of mixed glass beads of two different sizes. We focus on observing the approach of the time-dependent gas diffusion coefficient, D(t) (an indicator of mean squared displacement), to the long-time asymptote, with the aim of understanding the long-length scale structural information that may be derived from a heterogeneous porous system. We find that D(t) of imbibed xenon gas at short diffusion times is similar for the mixed bead pack and a pack of the smaller sized beads alone, hence reflecting the pore surface area to volume ratio of the smaller bead sample. The approach of D(t) to the long-time limit follows that of a pack of the larger sized beads alone, although the limiting D(t) for the mixed bead pack is lower, reflecting the lower porosity of the sample compared to that of a pack of mono-sized glass beads. The Pade approximation is used to interpolate D(t) data between the short- and long-time limits. Initial studies of continuous flow laser-polarized xenon gas demonstrate velocity-sensitive imaging of much higher flows than can generally be obtained with liquids (20-200 mm s-1). Gas velocity imaging is, however, found to be limited to a resolution of about 1 mm s-1 owing to the high diffusivity of gases compared with liquids. We also present the first gas-phase NMR scattering, or diffusive-diffraction, data, namely flow-enhanced structural features in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack. c2002 John Wiley & Sons, Ltd.

  13. Intramolecular hydrogen-bonding studies by NMR spectroscopy

    CERN Document Server

    Cantalapiedra, N A

    2000-01-01

    o-methoxybenzamide and N-methyl-o-methylbenzamide, using the pseudo-contact shifts calculated from the sup 1 H and sup 1 sup 3 C NMR spectra. The main conformation present in solution for o-fluorobenzamide was the one held by an intramolecular N-H...F hydrogen bond. Ab-initio calculations (at the RHF/6-31G* level) have provided additional data for the geometry of the individual molecules. A conformational equilibrium study of some nipecotic acid derivatives (3-substituted piperidines: CO sub 2 H, CO sub 2 Et, CONH sub 2 , CONHMe, CONEt sub 2) and cis-1,3-disubstituted cyclohexane derivatives (NHCOMe/CO sub 2 Me, NHCOMe/CONHMe, NH sub 2 /CO sub 2 H) has been undertaken in a variety of solvents, in order to predict the intramolecular hydrogen-bonding energies involved in the systems. The conformer populations were obtained by direct integration of proton peaks corresponding to the equatorial and axial conformations at low temperature (-80 deg), and by geometrically dependent coupling constants ( sup 3 J sub H s...

  14. 1H NMR relaxometry, viscometry, and PFG NMR studies of magnetic and nonmagnetic ionic liquids.

    Science.gov (United States)

    Daniel, Carla I; Chávez, Fabián Vaca; Feio, Gabriel; Portugal, Carla A M; Crespo, João G; Sebastião, Pedro J

    2013-10-03

    A study is presented of the molecular dynamics and of the viscosity in pure [Aliquat][Cl] ionic liquid and in a mixture of [Aliquat][Cl] with 1% (v/v) of [Aliquat][FeCl4]. The (1)H spin-lattice relaxation rate, R1, was measured by NMR relaxometry between 8 and 300 MHz. In addition, the translation self-diffusion, D, was measured by pulse field gradient NMR. The ILs' viscosity was measured as a function of an applied magnetic field, B, and it was found that the IL mixture's viscosity decreased with increasing B, whereas the [Aliquat][Cl] viscosity is independent of B. All experimental results were analyzed taking into account the viscosity's magnetic field dependence, assuming a modified Stokes-Einstein diffusion/viscosity relation. The main difference between the relaxation mechanisms responsible for R1 in the two IL systems is related to the additional paramagnetic relaxation contribution associated with the (1)H spins-[FeCl4] paramagnetic moments' interactions. Cross-relaxation cusps in the R1 dispersion, associated with (35)Cl and (1)H nuclear spins in the IL systems, were detected. The R1 model considered was successfully fitted to the experimental results, and it was possible to estimate the value of D at zero field in the case of the IL mixture which was consistent with the values of D measured at 7 and 14.1 T and with the magnetic field dependence estimated from the viscosity measurements. It was observed that a small concentration of [Aliquat][FeCl4] in the [Aliquat][Cl] was enough to produce a "superparamagnetic"-like effect and to change the IL mixture's molecular dynamics and viscosity and to allow for their control with an external magnetic field.

  15. NMR spectroscopic study on methanolysis reaction of vegetable oil

    Energy Technology Data Exchange (ETDEWEB)

    Fangming Jin; Kohei Kawasaki; Hisanori Kishida; Kazuyuki Tohji; Takehoko Moriya; Heiji Enomoto [Tohoku University, Sendai (Japan). Graduate School of Environmental Studies

    2007-05-15

    This study is to clarify the pathways of the transesterification of vegetable oil by applying NMR to the identification of intermediates in the transesterification reaction. Results showed that the significant methanolysis product was sn-1,3-diglycerides in diglycerides, and sn-2-monoglycerides was not found. These analytical results suggest that the methanolysis reaction may occur easily at the sn-2-position for both sn-tri- and sn-1,2-diglycerides. Short communication. 16 refs., 6 figs., 2 tabs.

  16. {sup 27}Al NMR studies of NpPd{sub 5}Al{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Chudo, H., E-mail: chudo.hiroyuki@jaea.go.j [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Sakai, H.; Tokunaga, Y.; Kambe, S. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Aoki, D.; Homma, Y.; Shiokawa, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Haga, Y.; Ikeda, S.; Matsuda, T.D. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Yasuoka, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2009-10-15

    We present {sup 27}Al NMR studies for a single crystal of the Np-based superconductor NpPd{sub 5}Al{sub 2}(T{sub c}=4.9K). We have observed a five-line {sup 27}Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T{sub c}. The temperature dependence of the {sup 27}Al nuclear spin-lattice relaxation rate shows no coherence peak below T{sub c}, indicating that NpPd{sub 5}Al{sub 2} is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd{sub 5}Al{sub 2}.

  17. 2H NMR studies of supercooled and glassy aspirin

    Science.gov (United States)

    Nath, R.; Nowaczyk, A.; Geil, B.; Bohmer, R.

    2007-11-01

    Acetyl salicylic acid, deuterated at the methyl group, was investigated using 2H-NMR in its supercooled and glassy states. Just above the glass transition temperature the molecular reorientations were studied using stimulated-echo spectroscopy and demonstrated a large degree of similarity with other glass formers. Deep in the glassy phase the NMR spectra look similar to those reported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they are indicative for rotational tunneling with a relatively large tunneling frequency. Measurements of the spin-lattice relaxation times for temperatures below 150 K reveal a broad distribution of correlation times in the glass. The dominant energy barrier characterizing the slow-down of the methyl group is significantly smaller than the well defined barrier in the crystal.

  18. Study of β-NMR for Liquid Biological Samples

    CERN Document Server

    Beattie, Caitlin

    2017-01-01

    β-NMR is an exotic form of NMR spectroscopy that allows for the characterization of matter based on the anisotropic β-decay of radioactive probe nuclei. This has been shown to be an effective spectroscopic technique for many different compounds, but its use for liquid biological samples is relatively unexplored. The work at the VITO line of ISOLDE seeks to employ this technique to study such samples. Currently, preparations are being made for an experiment to characterize DNA G-quadruplexes and their interactions with stabilizing cations. More specifically, the work in which I engaged as a summer student focused on the experiment’s liquid handling system and the stability of the relevant biological samples under vacuum.

  19. Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, R. [California Univ., Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)

    1993-07-01

    Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. {sup 27}Al and {sup 23}Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework {sup 27}Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na{sup +} cations are directly involved in adsorption processes and reactions in zeolite cavities.

  20. 1H NMR Studies of MgH2

    Science.gov (United States)

    Itoh, Yutaka; Kado, Ryoichi

    We report on 1H NMR studies of commercially available powder MgH2 exposed to air and maybe humidity, which has been believed to be a promising material for hydrogen storage. The Fourier transform of the free-induction decay of the protons indicatesd superposition of broad and narrow components in the NMR spectrum, while the Fourier transform of the 1H nuclear spin-echo reproduced the narrow component. With cooling down below room temperature, the ratio of the narrow peak to the broad spectrum decreased. The broad spectrum is associated with direct dipolar coupled protons on an inhomogeneous rigid lattice. The narrow peak is associated with interstitial protons with more inhomogeneous surroundings.

  1. Tacrine derivatives-acetylcholinesterase interaction: 1H NMR relaxation study.

    Science.gov (United States)

    Delfini, Maurizio; Di Cocco, Maria Enrica; Piccioni, Fabiana; Porcelli, Fernando; Borioni, Anna; Rodomonte, Andrea; Del Giudice, Maria Rosaria

    2007-06-01

    Two acetylcholinesterase (AChE) inhibitors structurally related to Tacrine, 6-methoxytacrine (1a) and 9-heptylamino-6-methoxytacrine (1b), and their interaction with Electrophorus Electricus AChE were investigated. The complete assignment of the 1H and 13C NMR spectra of 1a and 1b was performed by mono-dimensional and homo- and hetero-correlated two-dimensional NMR experiments. This study was undertaken to elucidate the interaction modes between AChE and 1a and 1b in solution, using NMR. The interaction between the two inhibitors and AChE was studied by the analysis of the motional parameters non-selective and selective spin-lattice relaxation times, thereby allowing the motional state of 1a and 1b, both free and bound with AChE, to be defined. The relaxation data pointed out the ligands molecular moiety most involved in the binding with AChE. The relevant ligand/enzyme interaction constants were also evaluated for both compounds and resulted to be 859 and 5412M(-1) for 1a and1b, respectively.

  2. Solution NMR studies on Helicobacter pylori proteins for antibiotic target discovery.

    Science.gov (United States)

    Lee, Ki-Young; Lee, Bong-Jin

    2016-07-01

    Helicobacter pylori (H. pylori) is a well-known widespread pathogenic bacterium that survives in the extremely acidic conditions of the human gastric mucosa. The global prevalence of H. pylori-resistant antibiotics has become an emerging issue in the 21st century and has necessitated the development of novel antibiotic drugs. Many efforts have aimed to discover antibiotic target proteins of H. pylori based on its genome of more than 1600 genes. This article highlights NMR spectroscopy as a valuable tool for determining the structure and dynamics of potential antibiotic-targeted proteins of H. pylori and evaluating their modes of interaction with native or synthetic binding partners. The residue-specific information on binding in solution provides a structural basis to identify and optimize lead compounds. NMR spectroscopy is a powerful method for obtaining details of biomolecular interactions with a broad range of binding affinities. This strength facilitates the identification of the binding interface of the encounter complex that plays an integral role in a variety of biological functions. This low-affinity complex is difficult to crystallize, which impedes structure determination using X-ray crystallography. Additionally, the relative binding affinities can be predicted from the type of spectral change upon binding. High-resolution NMR spectroscopy in combination with advanced computer simulation would provide more confidence in complex structures. The application of NMR to studies of the H. pylori protein could contribute to the development of these targeted novel antibiotics.

  3. Solid-state and unilateral NMR study of deterioration of a Dead Sea Scroll fragment.

    Science.gov (United States)

    Masic, A; Chierotti, M R; Gobetto, R; Martra, G; Rabin, I; Coluccia, S

    2012-02-01

    Unilateral and solid-state nuclear magnetic resonance (NMR) analyses were performed on a parchment fragment of the Dead Sea Scroll (DSS). The analyzed sample belongs to the collection of non-inscribed and nontreated fragments of known archaeological provenance from the John Rylands University Library in Manchester. Therefore, it can be considered as original DSS material free from any contamination related to the post-discovery period. Considering the paramount significance of the DSS, noninvasive approaches and portable in situ nondestructive methods are of fundamental importance for the determination of composition, structure, and chemical-physical properties of the materials under study. NMR studies reveal low amounts of water content associated with very short proton relaxation times, T(1), indicating a high level of deterioration of collagen molecules within scroll fragments. In addition, (13)C cross-polarization magic-angle-spinning (CPMAS) NMR spectroscopy shows characteristic peaks of lipids whose presence we attribute to the production technology that did not involve liming. Extraction with chloroform led to the reduction of both lipid and protein signals in the (13)C CPMAS spectrum indicating probable involvement of lipids in parchment degradation processes. NMR absorption and relaxation measurements provide nondestructive, discriminative, and sensitive tools for studying the deterioration effects on the organization and properties of water and collagen within ancient manuscripts.

  4. Solid-State NMR Studies of Chemically Lithiated CFx

    Science.gov (United States)

    Leifer, N. D.; Johnson, V. S.; Ben-Ari, R.; Gan, H.; Lehnes, J. M.; Guo, R.; Lu, W.; Muffoletto, B. C.; Reddy, T.; Stallworth, P. E.; Greenbaum, S. G.

    2010-01-01

    Three types of fluorinated carbon, all in their original form and upon sequential chemical lithiations via n-butyllithium, were investigated by 13C and 19F solid-state NMR methods. The three starting CFx materials [where x = 1 (nominally)] were fiber based, graphite based, and petroleum coke based. The aim of the current study was to identify, at the atomic/molecular structural level, factors that might account for differences in electrochemical performance among the different kinds of CFx. Differences were noted in the covalent F character among the starting compounds and in the details of LiF production among the lithiated samples. PMID:20676233

  5. NMR STUDY ON THE COMPATIBILITY OF ACR/PVC BLENDS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoqing; QIU Lingshi; WANG Dongsheng; WANG Yuanshen

    1988-01-01

    A 300MHz solid NMR study on the compatibility of ACR (poly (methyl methacrylate-co-methacrylate),in the ratio of 1:1)-PVC (poly (vinyl chloride)) blends is reported. Spin-lattice (T1) and spin-spin (T2)relaxation time of ACR, PVC and their blends are recorded in the temperature range from 215K to 355K.Experimental results indicate that ACR and PVC are compatible with each other and the domain size is smaller than 25 nm, but heterogeneities of molecular dimensions still exist. Some problems of mechanism of compatibility and data analysis are also discussed.

  6. Some double resonance and multiple quantum NMR studies in solids

    Energy Technology Data Exchange (ETDEWEB)

    Wemmer, D.E.

    1978-08-01

    The first section of this work presents the theory and experimental applications to analysis of molecular motion of chemical shielding lineshapes obtained with high resolution double resonance NMR techniques. Analysis of /sup 13/C powder lineshapes in hexamethylbenzene (HMB) and decamethylferrocene (DMFe) show that these molecules reorient in a jumping manner about the symmetry axis. Analysis of proton chemical shielding lineshapes of residual protons in heavy ice (D/sub 2/O) show that protons are exchanged among the tetrahedral positions of neighboring oxygen atoms, consistent with motion expected from defect migration. The second section describes the application of Fourier Transform Double Quantum NMR to measurement of chemical shielding of deuterium in powder samples. Studies of partially deuterated benzene and ferrocene give equal shielding anisotropies, ..delta..sigma = -6.5 ppM. Theoretical predictions and experimental measurements of dipolar couplings between deuterons using FTDQ NMR are presented. Crystals of BaClO/sub 3/.D/sub 2/O, ..cap alpha..,..beta.. d-2 HMB and ..cap alpha..,..beta..,..gamma.. d-3 HMB were studied, as were powders of d-2 HMB and anisic acid. The third section discusses general multiple quantum spectroscopy in dipolar coupled spin systems. Theoretical description is made for creation and detection of coherences between states without quantum number selection rules ..delta..m = +-1. Descriptions of techniques for partial selectivity of order in preparation and detection of multiple quantum coherences are made. The effects on selectivity and resolution of echo pulses during multiple quantum experiments are discussed. Experimental observation of coherences up to order 6 have been made in a sample of benzene dissolved in a liquid crystal. Experimental verifications of order selection and echo generation have been made.

  7. {sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Jennifer C., E-mail: jennifer.wilson@griffith.edu.au [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Laloo, Andrew Elohim [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia); Singh, Sanjesh [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Ferro, Vito, E-mail: v.ferro@uq.edu.au [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2014-01-03

    Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

  8. NMR study of hydroxy and amide protons in hyaluronan polymers.

    Science.gov (United States)

    Nestor, Gustav; Sandström, Corine

    2017-02-10

    Hyaluronan (HA) is an important and well characterized glycosaminoglycan with high viscosity and water-retaining capacity. Nonetheless, it is not fully understood whether conformational properties of the easily characterized HA oligomers can be transferred to HA polymers. To investigate possible differences in hydration, hydrogen bonding and flexibility between HA polymers and oligomers, hydroxy and amide protons of HA polymers were studied by solution-state and high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Measurements of chemical shifts, temperature coefficients and NOEs in HA polymers revealed that the NMR data are very similar compared to the interior of a HA octasaccharide, supporting transient hydrogen bond interactions across the β(1→3) and β(1→4) glycosidic linkages. However, differences in NOEs suggested a cis-like orientation between NH and H2 in the HA polymer. The lack of concentration dependence of the hydroxy proton chemical shifts suggests that there are no direct inter-chain interactions involving hydroxy protons at the concentrations investigated.

  9. NMR studies of two spliced leader RNAs using isotope labeling

    Energy Technology Data Exchange (ETDEWEB)

    Lapham, J.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

    1994-12-01

    Spliced leader RNAs are a class of RNA molecules (<200 nts) involved in the trans splicing of messenger RNA found in trypanosomes, nematodes, and other lower eukaryotes. The spliced leader RNA from the trypanosome Leptomonas Collosoma exists in two alternate structural forms with similar thermal stabilities. The 54 nucleotides on the 5{prime} end of the SL molecule is structurally independent from the 3{prime} half of the RNA, and displays the two structural forms. Furthermore, the favored of the two structures was shown to contain anomalous nuclease sensitivity and thermal stability features, which suggests that there may be tertiary interactions between the splice site and other nucleotides in the 5{prime} end. Multidimensional NMR studies are underway to elucidate the structural elements present in the SL RNAs that give rise to their physical properties. Two spliced leader sequences have been studied. The first, the 54 nucleotides on the 5{prime} end of the L. Collosoma sequence, was selected because of earlier studies in our laboratory. The second sequence is the 5{prime} end of the trypanosome Crithidia Fasciculata, which was chosen because of its greater sequence homology to other SL sequences. Given the complexity of the NMR spectra for RNA molecules of this size, we have incorporated {sup 15}N/{sup 13}C-labeled nucleotides into the RNA. One of the techniques we have developed to simplify the spectra of these RNA molecules is isotope labeling of specific regions of the RNA. This has been especially helpful in assigning the secondary structure of molecules that may be able to adopt multiple conformations. Using this technique one can examine a part of the molecule without spectral interference from the unlabeled portion. We hope this approach will promote an avenue for studying the structure of larger RNAs in their native surroundings.

  10. β-NMR study of boron in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Izumikawa, T., E-mail: izumika@med.niigata-u.ac.jp [Niigata University, Isotope Center (Japan); Mihara, M.; Matsuta, K.; Fukuda, M. [Osaka University, Department of Physics (Japan); Ohtsubo, T.; Ohya, S. [Niigata University, Graduate School of Science (Japan); Minamisono, T. [Osaka University, Department of Physics (Japan)

    2015-04-15

    A β-NMR study of {sup 12}B implanted in diamond was performed in order to investigate the implantation sites and the defects. The maintained polarization of {sup 12}B was measured by use of widely modulated rf around the Larmor frequency (ν = ν{sub L} ± 200 kHz) as a function of temperature from 160 K to 320 K. The observed polarization was found to be almost constant at about 0.9 % in this temperature range. The initial polarization for this system was obtained as about 8.1 %. Therefore about 10 % of the implanted {sup 12}B maintained its polarization in this frequency range. Conversely, about 90 % of the implanted {sup 12}B was undetected in the present experiment.

  11. Structural studies of proteins by paramagnetic solid-state NMR spectroscopy

    Science.gov (United States)

    Jaroniec, Christopher P.

    2015-04-01

    Paramagnetism-based nuclear pseudocontact shifts and spin relaxation enhancements contain a wealth of information in solid-state NMR spectra about electron-nucleus distances on the ∼20 Å length scale, far beyond that normally probed through measurements of nuclear dipolar couplings. Such data are especially vital in the context of structural studies of proteins and other biological molecules that suffer from a sparse number of experimentally-accessible atomic distances constraining their three-dimensional fold or intermolecular interactions. This perspective provides a brief overview of the recent developments and applications of paramagnetic magic-angle spinning NMR to biological systems, with primary focus on the investigations of metalloproteins and natively diamagnetic proteins modified with covalent paramagnetic tags.

  12. Structural studies of proteins by paramagnetic solid-state NMR spectroscopy

    Science.gov (United States)

    Jaroniec, Christopher P.

    2015-01-01

    Paramagnetism-based nuclear pseudocontact shifts and spin relaxation enhancements contain a wealth of information in solid-state NMR spectra about electron-nucleus distances on the ~20 Å length scale, far beyond that normally probed through measurements of nuclear dipolar couplings. Such data are especially vital in the context of structural studies of proteins and other biological molecules that suffer from a sparse number of experimentally-accessible atomic distances constraining their three-dimensional fold or intermolecular interactions. This perspective provides a brief overview of the recent developments and applications of paramagnetic magic-angle spinning NMR to biological systems, with primary focus on the investigations of metalloproteins and natively diamagnetic proteins modified with covalent paramagnetic tags. PMID:25797004

  13. NMR analysis of male fathead minnow urinary metabolites: A potential approach for studying impacts of chemical exposures

    Energy Technology Data Exchange (ETDEWEB)

    Ekman, D.R. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)], E-mail: ekman.drew@epa.gov; Teng, Q. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States); Jensen, K.M.; Martinovic, D.; Villeneuve, D.L.; Ankley, G.T. [Mid-Continent Ecology Division, U.S. EPA, 6201 Congdon Boulevard, Duluth, MN 55804 (United States); Collette, T.W. [Ecosystems Research Division, U.S. EPA, 960 College Station Road, Athens, GA 30605 (United States)

    2007-11-30

    The potential for profiling metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy was used for the assignment of metabolites in urine from unexposed fish. Because fathead minnow urine is dilute, we lyophilized these samples prior to analysis. Furthermore, 1D {sup 1}H NMR spectra of unlyophilized urine from unexposed male fathead minnow and Sprague-Dawley rat were acquired to qualitatively compare rat and fish metabolite profiles and to provide an estimate of the total urinary metabolite pool concentration difference. As a small proof-of-concept study, lyophilized urine samples from male fathead minnows exposed to three different concentrations of the antiandrogen vinclozolin were analyzed by 1D {sup 1}H NMR to assess exposure-induced changes. Through a combination of principal components analysis (PCA) and measurements of {sup 1}H NMR peak intensities, several metabolites were identified as changing with statistical significance in response to exposure. Among those changes occurring in response to exposure to the highest concentration (450 {mu}g/L) of vinclozolin were large increases in taurine, lactate, acetate, and formate. These increases coincided with a marked decrease in hippurate, a combination potentially indicative of hepatotoxicity. The results of these investigations clearly demonstrate the potential utility of an NMR-based approach for assessing chemical exposures in male fathead minnow, using urine collected from individual fish.

  14. Study of Conformation and Dynamics of Molecules Adsorbed in Zeolites by 1H NMR

    Science.gov (United States)

    Michel, Dieter; Bohlmann, Winfried; Roland, Jorg; Mulla-Osman, Samir

    The chapter Study of Conformation and Dynamics of Molecules Adsorbed in Zeolites by 1H NMR is concerned with the application of high-resolution (HR) solid-state NMR techniques to study the behavior of molecules adsorbed on surfaces of nanoporous solids, such as zeolitic molecular sieves. This includes a combined or alternative application of conventional high-resolution NMR methods and of high-resolution solid-state NMR techniques, including magic-angle sample spinning (MAS), cross-polarization (CP), high-power decoupling and appropriate multiple-pulse sequences for two- or higher dimensional NMR and multiple-quantum spectroscopy. The interaction of adsorbed molecules with adsorption centers in the internal surfaces of porous solids does not only lead to changes in the reorientational and translational mobility of the molecular species but influences also the molecular conformation. Examples will be given for simple olefins in interaction with inner zeolite surfaces. Conclusions about the correlation times of the internal reorientational and translational dynamics are derived in complete agreement with the conclusion obtained from diffusion coefficients by means of PFG NMR (second chapter). Since the methodical approach of HR MAS NMR in heterogeneous systems presented here is also valuable for the investigation of lyotropic crystalline phases using HR MAS NMR (in Chap. 12) And for the NMR studies of cartilage (in Chap. 13) it was also the aim of this chapter to elucidate also the methodical background of these measurements in some more detail.

  15. Temperature and pressure based NMR studies of detergent micelle phase equilibria.

    Science.gov (United States)

    Alvares, Rohan; Gupta, Shaan; Macdonald, Peter M; Prosser, R Scott

    2014-05-29

    Bulk thermodynamic and volumetric parameters (ΔGmic°, ΔHmic°, ΔSmic°, ΔCp,mic°, ΔVmic°, and Δκmic°) associated with the monomer–micelle equilibrium, were directly determined for a variety of common detergents [sodium n-dodecyl sulfate (SDS), n-dodecyl phosphocholine (DPC), n-dodecyl-β-d-maltoside (DDM), and 7-cyclohexyl-1-heptyl phosphocholine (CyF)] via 1H NMR spectroscopy. For each temperature and pressure point, the critical micelle concentration (cmc) was obtained from a single 1H NMR spectrum at a single intermediate concentration by referencing the observed chemical shift to those of pure monomer and pure micellar phases. This permitted rapid measurements of the cmc over a range of temperatures and pressures. In all cases, micelle formation was strongly entropically favored, while enthalpy changes were all positive, with the exception of SDS, which exhibited a modestly negative enthalpy of micellization. Heat capacity changes were also characteristically negative, while partial molar volume changes were uniformly positive, as expected for an aggregation process dictated by hydrophobic effects. Isothermal compressibility changes were found to be consistent with previous measurements using other techniques. Thermodynamic measurements were also related to spectroscopic studies of topology and micelle structure. For example, paramagnetic effects resulting from the addition of dioxygen provided microscopic topological details concerning the hydrophobicity gradient along the detergent chains within their respective micelles as detected by 1H NMR. In a second example, combined 13C and 1H NMR chemical shift changes arising from application of high pressure, or upon micellization, of CyF provided site-specific details regarding micelle topology. In this fashion, bulk thermodynamics could be related to microscopic topological details within the detergent micelle.

  16. Rovibrational and temperature effects in theoretical studies of NMR parameters

    DEFF Research Database (Denmark)

    Faber, Rasmus; Kaminsky, Jakub; Sauer, Stephan P. A.

    2016-01-01

    The demand for high precision calculations of NMR shieldings (or their related values, chemical shifts δ) and spin-spin coupling constants facilitating and supporting detailed interpretations of NMR spectra increases hand in hand with the development of computational techniques and hardware...... for molecular equilibrium geometries creates a demand for zero point vibrational and temperature corrections. In this chapter we describe briefly the theory behind rovibrational corrections and review then some important contributions to this field....

  17. Transformer-coupled NMR probe

    Science.gov (United States)

    Utsuzawa, Shin; Mandal, Soumyajit; Song, Yi-Qiao

    2012-03-01

    In this study, we propose an NMR probe circuit that uses a transformer with a ferromagnetic core for impedance matching. The ferromagnetic core provides a strong but confined coupling that result in efficient energy transfer between the sample coil and NMR spectrometer, while not disturbing the B1 field generated by the sample coil. We built a transformer-coupled NMR probe and found that it offers comparable performance (loss NQR.

  18. A strategy for co-translational folding studies of ribosome-bound nascent chain complexes using NMR spectroscopy.

    Science.gov (United States)

    Cassaignau, Anaïs M E; Launay, Hélène M M; Karyadi, Maria-Evangelia; Wang, Xiaolin; Waudby, Christopher A; Deckert, Annika; Robertson, Amy L; Christodoulou, John; Cabrita, Lisa D

    2016-08-01

    During biosynthesis on the ribosome, an elongating nascent polypeptide chain can begin to fold, in a process that is central to all living systems. Detailed structural studies of co-translational protein folding are now beginning to emerge; such studies were previously limited, at least in part, by the inherently dynamic nature of emerging nascent chains, which precluded most structural techniques. NMR spectroscopy is able to provide atomic-resolution information for ribosome-nascent chain complexes (RNCs), but it requires large quantities (≥10 mg) of homogeneous, isotopically labeled RNCs. Further challenges include limited sample working concentration and stability of the RNC sample (which contribute to weak NMR signals) and resonance broadening caused by attachment to the large (2.4-MDa) ribosomal complex. Here, we present a strategy to generate isotopically labeled RNCs in Escherichia coli that are suitable for NMR studies. Uniform translational arrest of the nascent chains is achieved using a stalling motif, and isotopically labeled RNCs are produced at high yield using high-cell-density E. coli growth conditions. Homogeneous RNCs are isolated by combining metal affinity chromatography (to isolate ribosome-bound species) with sucrose density centrifugation (to recover intact 70S monosomes). Sensitivity-optimized NMR spectroscopy is then applied to the RNCs, combined with a suite of parallel NMR and biochemical analyses to cross-validate their integrity, including RNC-optimized NMR diffusion measurements to report on ribosome attachment in situ. Comparative NMR studies of RNCs with the analogous isolated proteins permit a high-resolution description of the structure and dynamics of a nascent chain during its progressive biosynthesis on the ribosome.

  19. Mn(II) binding to human serum albumin: a ¹H-NMR relaxometric study.

    Science.gov (United States)

    Fanali, Gabriella; Cao, Yu; Ascenzi, Paolo; Fasano, Mauro

    2012-12-01

    Human serum albumin (HSA) displays several metal binding sites, participating to essential and toxic metal ions disposal and transport. The major Zn(II) binding site, called Site A, is located at the I/II domain interface, with residues His67, Asn99, His247, and Asp249 contributing with five donor atoms to the metal ion coordination. Additionally, one water molecule takes part of the octahedral coordination geometry. The occurrence of the metal-coordinated water molecule allows the investigation of the metal complex geometry by water (1)H-NMR relaxation, provided that the diamagnetic Zn(II) is replaced by the paramagnetic Mn(II). Here, the (1)H-NMR relaxometric study of Mn(II) binding to HSA is reported. Mn(II) binding to HSA is modulated by Zn(II), pH, and myristate through competitive inhibition and allosteric mechanisms. The body of results indicates that the primary binding site of Zn(II) corresponds to the secondary binding site of Mn(II), i.e. the multimetal binding site A. Excess Zn(II) completely displaces Mn(II) from its primary site suggesting that the primary Mn(II) site corresponds to the secondary Zn(II) site. This uncharacterized site is functionally-linked to FA1; moreover, metal ion binding is modulated by myristate and pH. Noteworthy, water (1)H-NMR relaxometry allowed a detailed analysis of thermodynamic properties of HSA-metal ion complexes.

  20. Studies of Molecular Dynamics by Solid State Deuterium NMR Spectroscopy

    Science.gov (United States)

    Zhao, Baiyi

    The rotational dynamics of molecules in a number of solid systems were followed by variable temperature deuterium (^2H), nuclear magnetic resonance (NMR) spectroscopy via changes in the spectral lineshapes and spin-lattice relaxation times (T _1). First the pure solid trimethylamine-borane adduct, (CH_3)_3NBH_3, was studied. For a methyl deuterated sample, T _1 measurements yielded two T_1 minima, 6.9 ms and 4.3 ms corresponding to the slowing of methyl and trimethyl rotation, respectively, with decreasing temperature. Activation energies for methyl and trimethyl rotation, obtained from fitting the T _1 curve as a function of temperature, were 32.8 and 15.0 kJ/mol, respectively; simulations of the spectral lineshapes gave 26.6 and 18.9 kT/mol, respectively. Fitting of the ^2H T_1 curve for the borane deuterated sample gave a BH _3 rotation activation energy of 14.1 kT/mol and a ^2H quadrupolar coupling constant, chi, of 101 kHz. The activation energy for BH_3 rotation obtained from the spectral lineshape simulations gave 12.6 kT/mol. A series of deuterated organic chalcogen cations: (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, were ion exchanged into the cavities of sodium Mordenite LZ-M5 and the dynamics of these guests within the hydrated zeolite were followed by ^2H NMR. All three undergo isotropic motion above about -80 to -90^circC. Below this temperature two superimposed ^2H powder spectra appear; the broad lineshape is consistent with only methyl rotation in a hindered, coordinated site, and the other narrow lineshape is due to both methyl and trimethyl rotation in a less hindered, uncoordinated site. As the temperature is lowered the population of the lower energy coordinated site increases. Relative peak areas yield adsorption enthalpies of 6.7, 7.8 and 10.0 kJ/mol for (CH_3)_3S^+, (CH_3)_3Se^+ and (CH_3)_3Te^+, respectively. The series of methyl deuterated ammonium and phosphonium cations: (CH_3)NH_3^+ , (CH_3)_2NH^+ , (CH_3)_3NH^+ and (CH_3)_4P^+ , were

  1. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β—Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    KaiJunLIAO; XiaoHuaYAN; 等

    2002-01-01

    The inclusion complex of lappaconitine(Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR,2D-NMR spectroscopy. The structure of the complex has been deduced.

  2. DSC and NMR Study on the Inclusion Complex of Lappaconitine with β-Cyclodextrin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The inclusion complex of lappaconitine (Lap) with β-cyclodextrin (β-CD) has been studied by the differential scanning calorimetry (DSC) and 1H-NMR, 2D-NMR spectroscopy.The structure of the complex has been deduced.``

  3. Supra-molecular structure and chemical reactivity of cellulose I studied using CP/MAS (sup)13 C-NMR

    CSIR Research Space (South Africa)

    Chunilall, Viren

    2013-08-01

    Full Text Available medium, provided the original work is properly cited. Supra-Molecular Structure and Chemical Reactivity of Cellulose I Studied Using CP/MAS 13C-NMR Viren Chunilall, Tamara Bush and Per Tomas Larsson Additional information is available at the end... of Cellulose I Studied Using CP/MAS 13C-NMR 71 1.1.2. Dissolving pulp The unbleached pulp that results after acid bi-sulphite pulping is used as raw material for dissolving pulp production. Lignin and hemicelluloses in the unbleached pulp are considered...

  4. Investigating sorption on iron-oxyhydroxide soil minerals by solid-state NMR spectroscopy: a 6Li MAS NMR study of adsorption and absorption on goethite

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Paik, Younkee; Julmis, Keinia;

    2005-01-01

    High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, th...

  5. Which kind of aromatic structures are produced during biomass charring? New insights provided by modern solid-state NMR spectroscopy

    Science.gov (United States)

    Knicker, Heike; Paneque-Carmona, Marina; Velasco-Molina, Marta; de la Rosa, José Maria; León-Ovelar, Laura Regina; Fernandez-Boy, Elena

    2017-04-01

    Intense research on biochar and charcoal of the last years has revealed that depending on the production conditions, the chemical and physical characteristics of their aromatic network can greatly vary. Since such variations are determining the behavior and stability of charred material in soils, a better understanding of the structural changes occurring during their heating and the impact of those changes on their function is needed. One method to characterize pyrogenic organic matter (PyOM) represents solid-state 13C NMR spectroscopy applying the cross polarization (CP) magic angle spinning technique (MAS). A drawback of this technique is that the quantification of NMR spectra of samples with highly condensed and proton-depleted structures is assumed to be bias. Typical samples with such attributes are charcoals produced at temperatures above 700°C under pyrolytic conditions. Commonly their high condensation degree leads to graphenic structures that are not only reducing the CP efficiency but create also a conductive lattice which acts as a shield and prevents the entering of the excitation pulse into the sample during the NMR experiments. Since the latter can damage the NMR probe and in the most cases the obtained NMR spectra show only one broad signal assignable to aromatic C, this technique is rarely applied for characterizing high temperature chars or soot. As a consequence, a more detailed knowledge of the nature of the aromatic ring systems is still missing. The latter is also true for the aromatic domains of PyOM produced at lower temperatures, since older NMR instruments operating at low magnetic fields deliver solid-state 13C NMR spectra with low resolution which turns a more detailed analysis of the aromatic chemical shift region into a challenging task. In order to overcome this disadvantages, modern NMR spectroscopy offers not only instruments with greatly improved resolution but also special pulse sequences for NMR experiments which allow a more

  6. Artefacts in 1H NMR-based metabolomic studies on cell cultures.

    Science.gov (United States)

    Madhu, Basetti; Dadulescu, Madalina; Griffiths, John

    2015-04-01

    Metabolomic studies on cultured cells involve assays of cell extracts and culture medium, both of which are often performed by (1)H NMR. Cell culture is nowadays performed in plastic dishes or flasks, and the extraction of metabolites from the cells is typically performed with perchloric acid, methanol-chloroform, or acetonitrile, ideally while the cells are still adherent to the culture dish. We conducted this investigation to identify contaminants from cell culture plasticware in metabolomic studies. Human diploid fibroblasts (IMR90) (n = 6), HeLa cells (n = 6), and transformed astrocytes with HIF-1 knockout (Astro-KO) (n = 6) were cultured. Cells were seeded in 100 mm Petri dishes with 10 ml complete growth medium (Dulbecco's minimum essential medium) containing 10 % foetal bovine serum (FBS). Cell cultures were incubated at 37 °C in 5 % CO2 for approximately 3 days. Metabolites were extracted by use of a perchloric acid procedure. (1)H NMR spectroscopy was used for metabolite analysis. "Null sample" (i.e. cell-free) experiments were performed by either rinsing dishes with medium or incubating the medium in Petri dishes from five different manufacturers for 72 h and then by performing a dummy "extraction" of each Petri dish by the perchloric acid, methanol-chloroform, or acetonitrile procedures. Principal components analysis was used for classification of samples and to determine the contaminants arising from plasticware. We found that even brief rinsing of cell culture plasticware with culture medium elutes artefactual chemicals, the (1)H NMR signals of which could confound assays of acetate, succinate, and glycolate. Incubation of culture medium in cell-culture dishes for 72 h (as in a typical cell-culture experiment) followed by perchloric extraction in the dishes enhanced elution of the artefacts. These artefacts were present, but somewhat less pronounced, in the (1)H NMR spectra of null samples extracted with methanol and acetonitrile. Ethanol, lactate

  7. Low-temperature NMR studies of Ce-Al compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gavilano, J.L. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Hunziker, J. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Vonlanthen, P. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland)); Ott, H.R. (Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, CH-8093 Zuerich (Switzerland))

    1994-04-01

    Ce-Al compounds display a variety of unconventional magnetic properties at low temperatures. This is particularly well demonstrated by the results of our low-frequency NMR studies on CeAl[sub 2], CeAl[sub 3] and Ce[sub 3]Al[sub 11]. Although CeAl[sub 2] orders antiferromagnetically below 3.4 K, the temperature dependence of the spin-lattice relaxation rate follows a Korringa law below 1 K. For CeAl[sub 3], we observe an increase of the line width below 0.9 K, but no indication of a phase transition is discernible from the temperature dependence of the spin-lattice relaxation rate. Ce[sub 3]Al[sub 11] is ferromagnetic below 6.2 K, but develops an antiferromagnetic and modulated structure below 3.3 K. A field of the order of 3 kG, however, appears to stabilize the ferromagnetic phase. Our spectroscopic data are important in view of some of the unusual thermal properties of these materials. ((orig.))

  8. Phenol-formaldehyde resins: A quantitative NMR study of molecular structure and molecular dynamics

    Science.gov (United States)

    Ottenbourgs, Benjamin Tony

    Phenol-formaldehyde (PF) resins have been the subject of this work. 13C liquid-state and solid-state NMR has been used to investigate the molecular structure of mainly novolak and partially of resole resins. 1H wideline in combination with 13C solid-state NMR relaxometry has been applied to study the curing and the molecular dynamics of phenolic resins. It was the intention to provide an insight in the relationship between resin composition, resin structure and subsequent resin properties (by means of the molecular dynamics). An improved 13C liquid-state NMR quantification technique of novolaks in THF-CDCl3 solutions is demonstrated. Full quantitative 13C liquid-state spectra of phenol-formaldehyde resins with high signal- to-noise ratio were obtained by using chromium acetylacetonate under optimized spectral conditions within a few hours spectrometer time. Attached proton test (APT) spectra enabled proper peak assignments in the region with significant overlap. For several novolaks, prepared under different catalytic conditions, the degree of polymerization, degree of branching, number average molecular weight, isomeric distribution, and the number of unreacted ortho and para phenol ring positions was determined with a reduced margin of error, by analyzing and integrating the 13C spectra. The power of 13C solid-state NMR in the analysis of cured PF resins is shown. Particular importance was ascribed to the question of the quantifiability of the experiments when it was desired to measure the degree of conversion by means of a 13C CP/MAS contact time study. The network structure present, and thus also the mechanical properties, is critically dependent upon the final degree of conversion obtained after curing. The degree of conversion, which depended on the cure conditions (cure temperature, cure pressure and cure time), was limited by vitrification as was demonstrated by DSC experiments. Changes in the spin-lattice relaxation time T 1H were observed, providing

  9. 2H NMR studies of glycerol dynamics in protein matrices.

    Science.gov (United States)

    Herbers, C R; Sauer, D; Vogel, M

    2012-03-28

    We use (2)H NMR spectroscopy to investigate the rotational motion of glycerol molecules in matrices provided by the connective tissue proteins elastin and collagen. Analyzing spin-lattice relaxation, line-shape properties, and stimulated-echo decays, we determine the rates and geometries of the motion as a function of temperature and composition. It is found that embedding glycerol in an elastin matrix leads to a mild slowdown of glycerol reorientation at low temperatures and glycerol concentrations, while the effect vanishes at ambient temperatures or high solvent content. Furthermore, it is observed that the nonexponential character of the rotational correlation functions is much more prominent in the elastin matrix than in the bulk liquid. Results from spin-lattice relaxation and line shape measurements indicate that, in the mixed systems, the strong nonexponentiality is in large part due to the existence of distributions of correlation times, which are broader on the long-time flank and, hence, more symmetric than in the neat system. Stimulated-echo analysis of slow glycerol dynamics reveals that, when elastin is added, the mechanism for the reorientation crosses over from small-angle jump dynamics to large-angle jump dynamics and the geometry of the motion changes from isotropic to anisotropic. The results are discussed against the background of present and previous findings for glycerol and water dynamics in various protein matrices and compared with observations for other dynamically highly asymmetric mixtures so as to ascertain in which way the viscous freezing of a fast component in the matrix of a slow component differs from the glassy slowdown in neat supercooled liquids.

  10. 2H NMR studies of glycerol dynamics in protein matrices

    Science.gov (United States)

    Herbers, C. R.; Sauer, D.; Vogel, M.

    2012-03-01

    We use 2H NMR spectroscopy to investigate the rotational motion of glycerol molecules in matrices provided by the connective tissue proteins elastin and collagen. Analyzing spin-lattice relaxation, line-shape properties, and stimulated-echo decays, we determine the rates and geometries of the motion as a function of temperature and composition. It is found that embedding glycerol in an elastin matrix leads to a mild slowdown of glycerol reorientation at low temperatures and glycerol concentrations, while the effect vanishes at ambient temperatures or high solvent content. Furthermore, it is observed that the nonexponential character of the rotational correlation functions is much more prominent in the elastin matrix than in the bulk liquid. Results from spin-lattice relaxation and line shape measurements indicate that, in the mixed systems, the strong nonexponentiality is in large part due to the existence of distributions of correlation times, which are broader on the long-time flank and, hence, more symmetric than in the neat system. Stimulated-echo analysis of slow glycerol dynamics reveals that, when elastin is added, the mechanism for the reorientation crosses over from small-angle jump dynamics to large-angle jump dynamics and the geometry of the motion changes from isotropic to anisotropic. The results are discussed against the background of present and previous findings for glycerol and water dynamics in various protein matrices and compared with observations for other dynamically highly asymmetric mixtures so as to ascertain in which way the viscous freezing of a fast component in the matrix of a slow component differs from the glassy slowdown in neat supercooled liquids.

  11. Lipid Dynamics Studied by Calculation of 31P Solid-State NMR Spectra Using Ensembles from Molecular Dynamics Simulations

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh; Vestergaard, Mikkel; Thøgersen, Lea;

    2014-01-01

    We present a method to calculate 31P solid-state NMR spectra based on the dynamic input from extended molecular dynamics (MD) simulations. The dynamic information confered by MD simulations is much more comprehensive than the information provided by traditional NMR dynamics models based on......, for example, order parameters. Therefore, valuable insight into the dynamics of biomolecules may be achieved by the present method. We have applied this method to study the dynamics of lipid bilayers containing the antimicrobial peptide alamethicin, and we show that the calculated 31P spectra obtained...

  12. 129Xe NMR studies of biochar made from biobased materials

    Science.gov (United States)

    Biochar is created by pyrolysis of biobased materials under controlled oxidative environments. The product is charcoal-like and can be used as filtration medium, sequestrant for metallic ions, soil conditioner, and other applications. In our work we have found 129Xe NMR to be an excellent technique...

  13. NMR and NQR study of the thermodynamically stable quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Shastri, Ananda [Iowa State Univ., Ames, IA (United States)

    1995-02-10

    27Al and 61,65Cu NMR measurements are reported for powder samples of stable AlCuFe and AlCuRu icosahedral quasicrystals and their crystalline approximants, and for a AlPdMn single grain quasicrystal. Furthermore, 27Al NQR spectra at 4.2 K have been observed in the AlCuFe and AlCuRu samples. From the quadrupole perturbed NMR spectra at different magnetic fields, and from the zero field NQR spectra, a wide distribution of local electric field gradient (EFG) tensor components and principal axis system orientations was found at the Al site. A model EFG calculation based on a 1/1 AlCuFe approximant was successful in explaining the observed NQR spectra. It is concluded that the average local gradient is largely determined by the p-electron wave function at the Al site, while the width of the distribution is due to the lattice contribution to the EFG. Comparison of 63Cu NMR with 27Al NMR shows that the EFG distribution at the two sites is similar, but that the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more s-type wave function of the conduction electrons.

  14. Dynamics in photosynthetic transient complexes studied by paramagnetic NMR spectroscopy

    NARCIS (Netherlands)

    Scanu, Sandra

    2013-01-01

    This PhD thesis focuses on fundamental aspects of protein-protein interactions. A multidisciplinary methodology for the detection and visualization of transient, lowly-populated encounter protein complexes is described. The new methodology combined paramagnetic NMR spectroscopy with computational

  15. Positional enrichment by proton analysis (PEPA). A one-dimensional {sup 1}H-NMR approach for {sup 13}C stable isotope tracer studies in metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Vinaixa, Maria; Yanes, Oscar [Department of Electronic Engineering-Universitat Rovira i Virgili, Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus (Spain); Rodriguez, Miguel A.; Capellades, Jordi [Universitat Rovira i Virgili, Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus (Spain); Aivio, Suvi; Stracker, Travis H. [Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (Spain); Gomez, Josep; Canyellas, Nicolau [Department of Electronic Engineering-, Universitat Rovira i Virgili, Tarragona (Spain)

    2017-03-20

    A novel metabolomics approach for NMR-based stable isotope tracer studies called PEPA is presented, and its performance validated using human cancer cells. PEPA detects the position of carbon label in isotopically enriched metabolites and quantifies fractional enrichment by indirect determination of {sup 13}C-satellite peaks using 1D-{sup 1}H-NMR spectra. In comparison with {sup 13}C-NMR, TOCSY and HSQC, PEPA improves sensitivity, accelerates the elucidation of {sup 13}C positions in labeled metabolites and the quantification of the percentage of stable isotope enrichment. Altogether, PEPA provides a novel framework for extending the high-throughput of {sup 1}H-NMR metabolic profiling to stable isotope tracing in metabolomics, facilitating and complementing the information derived from 2D-NMR experiments and expanding the range of isotopically enriched metabolites detected in cellular extracts. (copyright 2017 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

  16. Pulsed NMR studies of water under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    DeFries, Timothy Hatmaker

    1978-01-01

    The dynamic structure of water and heavy water was studied using NMR spin-lattice relaxation and self-diffusion techniques. For both compounds, the relaxation rate is proportional to the ratio of viscosity to absolute temperature at constant density. The coupling between rotational and translational motions decreases with increasing temperature and increasing density. The temperature and density dependence of the deuteron quadrupole coupling constant in D/sub 2/O was determined. The proton spin-lattice relaxation times of supercritical H/sub 2/O were measured from 400 to 700/sup 0/C and to 1 kbar. The times were found to be roughly proportional to density and were found to decrease with temperature. The angular momentum correlation times tau/sub J/ were calculated and compared with the times between collisions for a hard sphere fluid, the Enskog times, tau/sub E/. The values of tau/sub E//tau/sub J/ were roughly 6 at 400/sup 0/C and low densities. The values decreased at higher densities and higher temperatures. The proton spin-lattice relaxation times of H/sub 2/O were also measured from 90 to 350/sup 0/C up to 2 to 5 kbar. The data clearly show the change from dipolar to spin-rotation relaxation as a function of temperature and density. Both the low and the high temperature results agree with the idea that it is the strong and anisotropic intermolecular potential which causes the dynamic behavior of water to be so different from that of normal liquids.

  17. High pressure NMR study of a small protein, gurmarin

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Kyoko; Yamada, Hiroaki [Kobe University, Division of Molecular Science, Graduate School of Science and Technology, and Department of Chemistry, Faculty of Science (Japan); Imoto, Toshiaki [Tottori University, Faculty of Medicine (Japan); Akasaka, Kazuyuki [Kobe University, Division of Molecular Science, Graduate School of Science and Technology, and Department of Chemistry, Faculty of Science (Japan)

    1998-11-15

    The effect of pressure on the structure of gurmarin, a globular, 35-residue protein from Gymnema sylvestre, was studied in aqueous environment (95% 1H2O/5% 2H2O, pH 2.0) with an on-line variable pressure NMR system operating at 750 MHz. Two-dimensional TOCSY and NOESY spectra were measured as functions of pressure between 1 and 2000 bar at 40 deg. C . Practically all the proton signals of gurmarin underwent some shifts with pressure, showing that the entire protein structure responds to, and is altered by, pressure. Most amide protons showed different degrees of low field shifts with pressure, namely 0-0.2 ppm with an average of 0.051 ppm at 2000 bar, showing that they are involved in hydrogen bonding and that these hydrogen bonds are shortened by pressure by different degrees. The tendency was also confirmed that the chemical shifts of the amide protons exposed to the solvent (water) are more sensitive to pressure than those internally hydrogen bonded with carbonyls. The pressure-induced shifts of the H{alpha} signals of the residues in the {beta}-sheet showed a negative correlation with the 'folding' shifts (difference between the shift at 1 bar and that of a random coil), suggesting that the main-chain torsion angles of the {beta}-sheet are slightly altered by pressure. Significant pressure-induced shifts were also observed for the side-chain protons (but no larger than 10% of the 'folding' shifts), demonstrating that the tertiary structure of gurmarin is also affected by pressure. Finally, the linearity of the pressure-induced shifts suggests that the compressibility of gurmarin is invariant in the pressure range between 1 and 2000 bar.

  18. High temperature {sup 17}O MAS NMR study of calcia, magnesia, scandia and yttria stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Namjun; Stebbins, Jonathan F. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Hsieh, Cheng-Han [Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States); Huang, Hong [Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States); Prinz, Fritz B. [Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States); Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2007-11-15

    High-resolution {sup 17}O MAS NMR can provide unique constraints on local structure and oxide ion dynamics in conductive zirconia ceramics of interest for fuel cells and other technologies. We describe here NMR and bulk conductivity measurements for scandia, yttria, calcia, and magnesia stabilized zirconias, including MAS NMR spectra collected in situ at temperatures up to 700 C. All of the cubic compounds with high dopant levels showed line narrowing and coalescence in this temperature range, and the temperature-induced changes in line widths are qualitatively correlated with the bulk conductivities. A monoclinic zirconia with 2% Sc{sub 2}O{sub 3} dopant level (expected to have relatively low ionic mobility) showed no motional averaging of its two {sup 17}O NMR peaks even at 600 C, but instead is observed to begin to transform to a disordered, possibly cubic or tetragonal phase at 600 to 700 C. {sup 17}O MAS NMR spectra of calcia stabilized zirconia were analyzed in detail and the exchange frequencies as a function of temperature, conductivity, and activation energy were estimated and compared with bulk conductivities. The activation energy estimated from NMR exchange frequencies is somewhat lower than that of bulk conductivity but the conductivities estimated from NMR appear to be lower than bulk conductivity. (author)

  19. Studies of Secondary Melanoma on C57BL/6J Mouse Liver Using 1H NMR Metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Ju; Isern, Nancy G.; Burton, Sarah D.; Hu, Jian Z.

    2013-10-31

    NMR metabolomics, consisting of solid state high resolution (hr) magic angle spinning (MAS) 1H NMR (1H hr-MAS), liquid state high resolution 1H-NMR, and principal components analysis (PCA) has been used to study secondary metastatic B16-F10 melanoma in C57BL/6J mouse liver . The melanoma group can be differentiated from its control group by PCA analysis of the absolute concentrations or by the absolute peak intensities of metabolites from either 1H hr-MAS NMR data on intact liver tissues or liquid state 1H-NMR spectra on liver tissue extracts. In particular, we found that the absolute concentrations of alanine, glutamate, creatine, creatinine, fumarate and cholesterol are elevated in the melanoma group as compared to controls, while the absolute concentrations of succinate, glycine, glucose, and the family of linear lipids including long chain fatty acids, total choline and acylglycerol are decreased. The ratio of glycerophosphocholine to phosphocholine is increased by about 1.5 fold in the melanoma group, while the absolute concentration of total choline is actually lower in melanoma mice. These results suggest the following picture in secondary melanoma metastasis: Linear lipid levels are decreased by beta oxidation in the melanoma group, which contributes to an increase in the synthesis of cholesterol, and also provides an energy source input for TCA cycle. These findings suggest a link between lipid oxidation, the TCA cycle and the hypoxia-inducible factors (HIF) signal pathway in tumor metastases. Thus this study indicates that the metabolic profile derived from NMR analysis can provide a valuable bio-signature of malignancy and cell hypoxia in metastatic melanoma.

  20. A combined solid-state NMR and X-ray crystallography study of the bromide ion environments in triphenylphosphonium bromides.

    Science.gov (United States)

    Burgess, Kevin M N; Korobkov, Ilia; Bryce, David L

    2012-04-27

    Multinuclear ((31)P and (79/81)Br), multifield (9.4, 11.75, and 21.1 T) solid-state nuclear magnetic resonance experiments are performed for seven phosphonium bromides bearing the triphenylphosphonium cation, a molecular scaffold found in many applications in chemistry. This is undertaken to fully characterise their bromine electric field gradient (EFG) tensors, as well as the chemical shift (CS) tensors of both the halogen and the phosphorus nuclei, providing a rare and novel insight into the local electronic environments surrounding them. New crystal structures, obtained from single-crystal X-ray diffraction, are reported for six compounds to aid in the interpretation of the NMR data. Among them is a new structure of BrPPh(4), because the previously reported one was inconsistent with our magnetic resonance data, thereby demonstrating how NMR data of non-standard nuclei can correct or improve X-ray diffraction data. Our results indicate that, despite sizable quadrupolar interactions, (79/81)Br magnetic resonance spectroscopy is a powerful characterisation tool that allows for the differentiation between chemically similar bromine sites, as shown through the range in the characteristic NMR parameters. (35/37)Cl solid-state NMR data, obtained for an analogous phosphonium chloride sample, provide insight into the relationship between unit cell volume, nuclear quadrupolar coupling constants, and Sternheimer antishielding factors. The experimental findings are complemented by gauge-including projector-augmented wave (GIPAW) DFT calculations, which substantiate our experimentally determined strong dependence of the largest component of the bromine CS tensor, δ(11), on the shortest Br-P distance in the crystal structure, a finding that has possible application in the field of NMR crystallography. This trend is explained in terms of Ramsey's theory on paramagnetic shielding. Overall, this work demonstrates how careful NMR studies of underexploited exotic nuclides, such

  1. 125Te NMR study of IrTe 2

    Science.gov (United States)

    Mizuno, Kiyoshi; Magishi, Ko-ichi; Shinonome, Yasuaki; Saito, Takahito; Koyama, Kuniyuki; Matsumoto, Nobuhiro; Nagata, Shoichi

    2002-03-01

    We have measured 125Te NMR of IrTe2 in order to elucidate the origin of the anomalous behaviors in electrical and magnetic properties around 270 K. In high-temperature region, the NMR spectrum exhibits a sharp line. On the other hand, in low-temperature region, the spectrum shifts to higher magnetic field and splits into three lines. Also, the nuclear spin-lattice relaxation rate, 1/T1, is proportional to the temperature in both temperature sides; Korringa-like behavior which is characteristic of a metallic state. From the T dependences of the spectrum and 1/T1 around 270 K, it is suggested that these anomalous behaviors may not be due to the charge density wave formation but be caused by a kind of lattice distortion at low temperature.

  2. Isolation and NMR Study on Swainsonine from Locoweed, Astragalus strictus

    Institute of Scientific and Technical Information of China (English)

    ZHAO Bao-yu; LIU Zhong-yan; WANG Jian-jun; SUN Li-sha; WANG Zhan-xin; WANG Yin-chao

    2009-01-01

    Locoweed is a poisonous plant wildly distributed in most area of the world and can cause livestock poisoning or death with significant economic loss. The principal responsible for its toxicity is indolizidine alkaloid swainsonine, a new potential anticancer and antiviral drug. Astragalus strictus is mainly distributed in Tibet of China and is a serious hazard to the local livestock industry. To analyze its main toxic ingredients and supply more structural information and more accurate data, swainsonine has been isolated from this plant by D101 macroporous resin and the 1H and 13C chemical shifts of the compound has been assigned by 1D-NMR and 2D-NMR techniques. At the same time, complete assignments of swainsonine's 13C spectral signals are reported.

  3. Study of Magnetic Nanocomposites by NMR and Bulk Magnetization Techniques

    Directory of Open Access Journals (Sweden)

    Matveev V.

    2014-07-01

    Full Text Available Magnetic nanocomposites possess complex and nonuniform magnetic structure. As a result it is necessary to use different physical methods to describe their properties. In this work we have applied a combination of micro and macro approaches to understand more deeply magnetic properties of some cobaltcontaining nanocomposites. Testing of magnetic structure of the samples at molecular level was done with NMR and Mössbauer techniques whereas static (SQUID and dynamic magnetic (M2, see below measurements – at macro level.

  4. NMR Studies of Lithium Iodide Based Solid Electrolytes

    DEFF Research Database (Denmark)

    Dupree, R.; Howells, R. J.; Hooper, A.

    1983-01-01

    In mixture of LiI with γAl2O3 the ionic conductivity is found to increase by up to three orders of magnitude over pure LiI. NMR measurements of7Li relaxation times were performed on both anhydrous LiI and a mixture of LiI with 30m/o γAl2O3. The relaxation is found to be purely dipolar in origin f...

  5. NMR spectroscopy study of agar-based polymers electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, R.I.; Tambelli, C.E. [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Fac. de Zootecnia e Engenharia de Alimentos; Raphael, E. [Universidade Federal de Sao Joao del-Rey (UFSJ), MG (Brazil). Dept. de Ciencias Naturais; Silva, I.D.A.; Magon, C.J.; Donoso, J.P. [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2012-07-01

    Full text: This communication presents the results of preparation and characterization of transparent films obtained from agar and acetic acid. The films were characterized by electrochemical impedance spectroscopy (EIS) and nuclear magnetic resonance (NMR). The film formed by agar (Sigma Aldrich) was dispersed in water and kept under stirring and heating at 100 deg C. Next, glycerol, formaldehyde and different quantities of acetic acid (25 and 50 wt%) were added to this solution. The obtained solution was placed on a glass plate and left to dry for 48 hours in oven at 50 deg C to obtain the films, which were kept under vacuum before characterization. The ionic conductivity of the films display an Arrhenius behavior with activation energy E{sub a} = 78 (25 wt% of acetic acid) and E{sub a} = 87 kJ/mol (50 wt% of acetic acid). The conductivity values were 3:0 X 10{sup -6} and 1:2 X 10{sup -4} S/cm at room temperature and 4:4 X 10{sup -4} and 1:5 X 10{sup -3}S/cm at 70 deg C, for the 25 and 50 wt% of acetic acid respectively. To investigate the mechanism of protonic conduction in the polymer proton conductor proton NMR measurements were performed in the temperature range 200-370 K. The {sup 1}H-NMR results exhibit the qualitative feature associated with the proton mobility, namely the presence of well defined {sup 1}H spin-lattice relaxation maxima at 300 K. Activation energy of the order of 40 kJ/mol was obtained from the {sup 1}H-NMR line narrowing data. The ionic conductivity of the film combined with their transparency, flexibility, homogeneity and good adhesion to the glasses or metals indicate that agar-based SPEs are promising materials for used on optoelectronic applications. (author)

  6. A study of sup 3 He films using SQUID NMR

    CERN Document Server

    Dyball, H C J

    2001-01-01

    Confinement of superfluid sup 3 He to a geometry of order the coherence length is predicted to produce interesting size effects and modify the superfluid phase diagram. This thesis describes the development of an experiment to measure these effects using NMR as a probe of the spin dynamics. A pulsed NMR spectrometer was developed with a low T sub c SQUID as the first stage amplifier. The sample was located in a receiver coil that formed part of a tuned circuit with the SQUID input coil. The first spectrometer was operated in an open-loop configuration but was later converted to use feedback to stabilize the SQUID gain. This later version used a DC SQUID with APF operating in flux-locked loop using the Direct Offset Integration Technique. The noise was limited by the Johnson noise in the tuned circuit in tests down to 1.5 K and the estimated noise temperature was approx 100 mK. NMR signals were observed at approx 1 MHz from low-density sup 3 He samples adsorbed on a Mylar substrate which were in reasonable agr...

  7. O-17 NMR studies of some silicate crystals and glasses

    CERN Document Server

    Yildirim, E K

    2000-01-01

    structure. Therefore some of the Sn has to be in three coordinated to oxygen for charge balancing. The sup 1 sup 7 O MAS NMR spectra of a partially crystallised sample showed three distinct sites which are assigned as Sn-O-Sn, Si-O-Sn, and Si-O-Si on the basis of their chemical shift. The C sub Q values obtained from the simulations of these peaks supports this assignment. The sup 2 sup 9 Si MAS NMR of the same sample showed two crystalline and a glassy peaks which are fitted to two crystalline and two glassy sites. The possible composition of this sample was calculated and found to be SiSn sub 8 O sub 1 sub 0. Crystalline and glassy silicates were investigated by means of sup 1 sup 7 O NMR. The dependence of the measured efg on the Si-O-AI bond angle was investigated in some crystalline aluminosilicate sodalites and kalsilite. The results show that C sub Q increases with increasing bond angle while eta decreases with increasing bond angle and they both follow a similar function to that found for the Si-O-Si ...

  8. Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    different and cytolytic peptides were investigated in this work. The peptides were SPF-5506-A4 from Trichoderma sp, Conolysin-Mt1 from Conus mustelinus, and Alamethicin from Trichoderma viride. The studies employed solution and solid-state NMR spectroscopy in combination with different biophysical methods......- and 2H-labelled peptides. While the solution NMR experiments were performed to determine the structure of SPF-5506-A4 and Conolysin-Mt1, the oriented solid-state NMR experiments served to derive information about the orientation of the peptides with respect to the bilayer normal in order to understand...

  9. Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

    2012-07-01

    The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

  10. Authenticity study of Phyllanthus species by NMR and FT-IR Techniques coupled with chemometric methods

    Directory of Open Access Journals (Sweden)

    Maiara S. Santos

    2012-01-01

    Full Text Available The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as "quebra-pedras" in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques.

  11. NMR Study of the Dimerized State in CuIr{sub 2}S{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Ken-ichi, E-mail: kumagai@phys.sci.hokudai.ac.jp; Sasaki, Mayumi; Kakuyanagi, Kosuke [Hokkaido University, Division of Physics, Graduate School of Science (Japan); Nagata, Shoichi [Muroran Institute of Technology, Department of Materials Science and Engineering (Japan)

    2004-12-15

    We have investigated the metal-insulator transition (MIT) of CuIr{sub 2}S{sub 4} by a high resolution NMR measurement. The Cu-NMR spectrum below T{sub MI} is broadened and split into four Cu signals with sizable electric quadrupole interactions. The NMR results are consistent with the charge ordering of Ir{sup 3+} and Ir{sup 4+} and the spin dimerization of Ir{sup 4+} spins, as revealed by a recent X-ray study.

  12. NMR relaxation and micro-imaging study of polystyrene in concentrated cyclohexane solution

    Institute of Scientific and Technical Information of China (English)

    毛诗珍; 丁广良; 袁汉珍; 冯汉桥; 杜有如

    1997-01-01

    13C-NMR relaxation times of polystyrene (PS) in its 8 solvent, cyclohexane, are measured at different temperatures. A two-step model for the dissolution is proposed. Swelling of the polymer below the 8 temperature is eventually the dispersion of the side group phenyl rings only. While above the 6 temperature, complete dissolution is the dispersion of the main chain at a molecular level. The results of T1(C) are confirmed by 1H-NMR imaging. NMR and its imaging are powerful tools to study the dynamic behavior of dissolution process of polymers in their 6 solvents.

  13. TG/DTG, FT-ICR Mass Spectrometry, and NMR Spectroscopy Study of Heavy Fuel Oil

    KAUST Repository

    Elbaz, Ayman M.

    2015-11-12

    There is an increasing interest in the comprehensive study of heavy fuel oil (HFO) due to its growing use in furnaces, boilers, marines, and recently in gas turbines. In this work, the thermal combustion characteristics and chemical composition of HFO were investigated using a range of techniques. Thermogravimetric analysis (TGA) was conducted to study the nonisothermal HFO combustion behavior. Chemical characterization of HFO was accomplished using various standard methods in addition to direct infusion atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry (APCI-FTICR MS), high resolution 1H nuclear magnetic resonance (NMR), 13C NMR, and two-dimensional heteronuclear multiple bond correlation (HMBC) spectroscopy. By analyzing thermogravimetry and differential thermogravimetry (TG/DTG) results, three different reaction regions were identified in the combustion of HFO with air, specifically, low temperature oxidation region (LTO), fuel deposition (FD), and high temperature oxidation (HTO) region. At the high end of the LTO region, a mass transfer resistance (skin effect) was evident. Kinetic analysis in LTO and HTO regions was conducted using two different kinetic models to calculate the apparent activation energy. In both models, HTO activation energies are higher than those for LTO. The FT-ICR MS technique resolved thousands of aromatic and sulfur containing compounds in the HFO sample and provided compositional details for individual molecules of three major class species. The major classes of compounds included species with one sulfur atom (S1), with two sulfur atoms (S2), and purely hydrocarbons (HC). The DBE (double bond equivalent) abundance plots established for S1 and HC provided additional information on their distributions in the HFO sample. The 1H NMR and 13C NMR results revealed that nearly 59% of the 1H nuclei were distributed as paraffinic CH2 and 5% were in aromatic groups. Nearly 21% of 13C nuclei were

  14. High Resolution Magic Angle Spinning Nuclear Magnetic Resonance (HRMAS NMR) for Studies of Reactive Fabrics

    Science.gov (United States)

    2015-11-01

    Magnetic Resonance (HRMAS NMR) for Studies of Reactive Fabrics 5a. CONTRACT NUMBER W911SR-11-C-0047 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...ECBC-TR-1326 HIGH RESOLUTION MAGIC ANGLE SPINNING NUCLEAR MAGNETIC RESONANCE (HRMAS NMR) FOR STUDIES OF REACTIVE FABRICS David J. McGarvey...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT An analytical chemistry method is described for measuring the reactivity and permeation of

  15. Synthesis and NMR Spectral Studies of the 7-C60-Adduct of N,N-(Tetrachlorophthaloyl Dehydroabietylamine

    Directory of Open Access Journals (Sweden)

    Zhi Zhou

    2012-04-01

    Full Text Available The 7-C60-adduct of N,N-(tetrachlorophthaloyldehydroabietylamine was synthesized for the first time and characterized by IR, UV-vis, mass and NMR spectral studies. The 1H-NMR and 13C-NMR resonance signals of the new compound are unambiguously assigned by using homo- and heteronuclear 2D NMR spectroscopic techniques such as COSY, ROESY, HSQC and HMBC. The C1 symmetric structure with 6,6-junction of compound was determined.

  16. 29Si and 27AI MAS NMR Study of Alkali Feldspars

    Institute of Scientific and Technical Information of China (English)

    周玲棣; 郭九皋; 袁汉珍; 李丽云

    1994-01-01

    12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.

  17. Standardizing the experimental conditions for using urine in NMR-based metabolomic studies with a particular focus on diagnostic studies: a review

    KAUST Repository

    Emwas, Abdul-Hamid M.

    2014-11-21

    The metabolic composition of human biofluids can provide important diagnostic and prognostic information. Among the biofluids most commonly analyzed in metabolomic studies, urine appears to be particularly useful. It is abundant, readily available, easily stored and can be collected by simple, noninvasive techniques. Moreover, given its chemical complexity, urine is particularly rich in potential disease biomarkers. This makes it an ideal biofluid for detecting or monitoring disease processes. Among the metabolomic tools available for urine analysis, NMR spectroscopy has proven to be particularly well-suited, because the technique is highly reproducible and requires minimal sample handling. As it permits the identification and quantification of a wide range of compounds, independent of their chemical properties, NMR spectroscopy has been frequently used to detect or discover disease fingerprints and biomarkers in urine. Although protocols for NMR data acquisition and processing have been standardized, no consensus on protocols for urine sample selection, collection, storage and preparation in NMR-based metabolomic studies have been developed. This lack of consensus may be leading to spurious biomarkers being reported and may account for a general lack of reproducibility between laboratories. Here, we review a large number of published studies on NMR-based urine metabolic profiling with the aim of identifying key variables that may affect the results of metabolomics studies. From this survey, we identify a number of issues that require either standardization or careful accounting in experimental design and provide some recommendations for urine collection, sample preparation and data acquisition.

  18. Fundamentals of Protein NMR Spectroscopy

    CERN Document Server

    Rule, Gordon S

    2006-01-01

    NMR spectroscopy has proven to be a powerful technique to study the structure and dynamics of biological macromolecules. Fundamentals of Protein NMR Spectroscopy is a comprehensive textbook that guides the reader from a basic understanding of the phenomenological properties of magnetic resonance to the application and interpretation of modern multi-dimensional NMR experiments on 15N/13C-labeled proteins. Beginning with elementary quantum mechanics, a set of practical rules is presented and used to describe many commonly employed multi-dimensional, multi-nuclear NMR pulse sequences. A modular analysis of NMR pulse sequence building blocks also provides a basis for understanding and developing novel pulse programs. This text not only covers topics from chemical shift assignment to protein structure refinement, as well as the analysis of protein dynamics and chemical kinetics, but also provides a practical guide to many aspects of modern spectrometer hardware, sample preparation, experimental set-up, and data pr...

  19. NMR Study of Water Distribution inside Tomato Cells: Effects of Water Stress

    OpenAIRE

    Musse, M.; Cambert, M.; Mariette, F.

    2010-01-01

    Tomato pericarp tissue was studied by low-field nuclear magnetic res-onance (NMR) relaxometry. Two kinds of experiments were performed to inves-tigate the correlation between multi-exponential NMR relaxation and the subcellular compartments. The longitudinal (T 1 ) versus transverse (T 2 ) relaxation times were first measured on fresh samples and then the transverse relaxation time was measured on samples exposed to water stress. Four signal components were found in all experiments. The resul...

  20. NMR studies on antitumor drug candidates, berberine and berberrubine

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Young Wook; Jung, Jin Won; Kang, Mi Ran; Chung, In Kwon; Lee, Weon Tae [Yonsei Univ., Seoul (Korea, Republic of)

    2002-03-01

    Berberine and berberrubine, which display antitumor activity, have also demonstrated distinct enzyme-poisoning activities by stabilizing topoisomerase II-DNA cleavable complexes. The protoberberine berberrubine differs in chemical structure with berberine at only one position, however, it shows a prominent activity different from berberine. Solution structures of berberine and berberrubine determined by NMR spectroscopy are similar, however, the minor structural rearrangement has been observed near 19 methoxy or hydroxyl group. We suggest that the DNA cleavage activities of topoisomerase II poisons could be correlated with both chemical environments and minor structural change together with hydrophobicity of interacting side chains of drugs with DNA molecules.

  1. An NMR Study on Chrysathain%马钱苷的NMR数据解析

    Institute of Scientific and Technical Information of China (English)

    范毅; 张海艳; 李坤威; 张剑; 赵天增

    2014-01-01

    通过DEPT及1H-1HCOSY,HSQC,HMBC,NOESY等2D NMR技术,对环烯醚萜苷化合物--马钱苷的1H和13C NMR信号进行了详细解析和全归属,尤其利用NOESY技术确证了其立体结构。%Loganin,an important iro doid,was usually isolated from Cornus officinalis Sieb,et Zucc. and Lonicera chrysatha Thunb.. The 1H and 13C NMR chemical shifts of loganin were completely assigned by using a combination of 1D NMR(1H,13C NMR and DEPT)and 2D NMR(1H- 1H COSY,HSQC,HMBC and NOESY)techniques, especially its stereoscopic strcture was studied with NOESY.

  2. Compact NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bluemich, Bernhard; Haber-Pohlmeier, Sabina; Zia, Wasif [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMC)

    2014-06-01

    Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

  3. NMR Studies of the Structure and Function of the HIV-1 5'-Leader.

    Science.gov (United States)

    Keane, Sarah C; Summers, Michael F

    2016-12-21

    The 5'-leader of the human immunodeficiency virus type 1 (HIV-1) genome plays several critical roles during viral replication, including differentially establishing mRNA versus genomic RNA (gRNA) fates. As observed for proteins, the function of the RNA is tightly regulated by its structure, and a common paradigm has been that genome function is temporally modulated by structural changes in the 5'-leader. Over the past 30 years, combinations of nucleotide reactivity mapping experiments with biochemistry, mutagenesis, and phylogenetic studies have provided clues regarding the secondary structures of stretches of residues within the leader that adopt functionally discrete domains. More recently, nuclear magnetic resonance (NMR) spectroscopy approaches have been developed that enable direct detection of intra- and inter-molecular interactions within the intact leader, providing detailed insights into the structural determinants and mechanisms that regulate HIV-1 genome packaging and function.

  4. NMR study of CeTe at low temperatures

    Science.gov (United States)

    Hinderer, J.; Weyeneth, S. M.; Weller, M.; Gavilano, J. L.; Felder, E.; Hulliger, F.; Ott, H. R.

    2006-05-01

    We present 125Te NMR measurements on CeTe powder at temperatures between 1 and 150 K and in magnetic fields between 5 and 8 T. CeTe is a rocksalt-type intermetallic compound. It orders antiferromagnetically at TN≈2.2 K with a much reduced ordered moment [H.R. Ott, J.K. Kjems, F. Hulliger, Phys. Rev. Lett. 42 20 (1979) 1378]. From our low-temperature NMR spectra we infer the presence of at least three inequivalent Te sites at low temperatures. Considering the crystal structure this result is completely unexpected. The linewidths and the Knight shifts of the individual lines are significantly different and increase substantially with decreasing temperature. They follow the temperature dependence of the magnetic susceptibility above 20 K. Above TN, hyperfine fields of 1.6, 0.8 and 0.0 T at the three Te sites per Bohr magneton of Ce moment are deduced from Knight shift vs. magnetic susceptibility data. These values are typical for transferred hyperfine fields via conduction electrons.

  5. Dynamical properties of confined supercooled water: an NMR study

    Science.gov (United States)

    Mallamace, Francesco; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li; Mou, Chung-Yuan; Chen, Sow-Hsin

    2006-09-01

    We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190 K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d = 14,18 and 24 Å. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200 K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at TL = 225 K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature TL.

  6. Dynamical properties of confined supercooled water: an NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Broccio, Matteo [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Corsaro, Carmelo [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Faraone, Antonio [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Liu Li [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Mou, C-Y [Department of Chemistry, National Taiwan University, Taipei, Taiwan (China); Chen, S-H [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2006-09-13

    We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190 K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d = 14,18 and 24 A. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200 K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at T{sub L} = 225 K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature T{sub L}.

  7. 13C NMR relaxation studies on cartilage and cartilage components.

    Science.gov (United States)

    Naji, L; Kaufmann, J; Huster, D; Schiller, J; Arnold, K

    2000-08-07

    We have investigated the molecular motions of polysaccharides of bovine nasal and pig articular cartilage by measuring the 13C NMR relaxation times (T1 and T2). Both types of cartilage differ significantly towards their collagen/glycosaminoglycan ratio, leading to different NMR spectra. As chondroitin sulfate is the main constituent of cartilage, aqueous solutions of related poly- and monosaccharides (N-acetylglucosamine and glucuronic acid) were also investigated. Although there are only slight differences in T1 relaxation of the mono- and the polysaccharides, T2 decreases about one order of magnitude, when glucuronic acid or N-acetylglucosamine and chondroitin sulfate are compared. It is concluded that the ring carbons are motion-restricted primarily by the embedment in the rigid pyranose structure and, thus, additional limitations of mobility do not more show a major effect. Significant differences were observed between bovine nasal and pig articular cartilage, resulting in a considerable line-broadening and a lower signal to noise ratio in the spectra of pig articular cartilage. This is most likely caused by the higher collagen content of articular cartilage in comparison to the polysaccharide-rich bovine nasal cartilage.

  8. A Field Study of NMR Logging to Quantify Petroleum Contamination in Subsurface Sediments

    Science.gov (United States)

    Fay, E. L.; Knight, R. J.; Grunewald, E. D.

    2016-12-01

    Nuclear magnetic resonance (NMR) measurements are directly sensitive to hydrogen-bearing fluids including water and petroleum products. NMR logging tools can be used to detect and quantify petroleum hydrocarbon contamination in the sediments surrounding a well or borehole. An advantage of the NMR method is that data can be collected in both cased and uncased holes. In order to estimate the volume of in-situ hydrocarbon, there must be sufficient contrast between either the relaxation times (T2) or the diffusion coefficients (D) of water and the contaminant. In a field study conducted in Pine Ridge, South Dakota, NMR logging measurements were used to investigate an area of hydrocarbon contamination from leaking underground storage tanks. A contaminant sample recovered from a monitoring well at the site was found to be consistent with a mixture of gasoline and diesel fuel. NMR measurements were collected in two PVC-cased monitoring wells; D and T2 measurements were used together to detect and quantify contaminant in the sediments above and below the water table at both of the wells. While the contrast in D between the fluids was found to be inadequate for fluid typing, the T2 contrast between the contaminant and water in silt enabled the estimation of the water and contaminant volumes. This study shows that NMR logging can be used to detect and quantify in-situ contamination, but also highlights the importance of sediment and contaminant properties that lead to a sufficiently large contrast in T2 or D.

  9. A neutron-X-ray, NMR and calorimetric study of glassy Probucol synthesized using containerless techniques

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.K.R., E-mail: rweber@anl.gov [Materials Development, Inc., Arlington Heights, IL 60004 (United States); Argonne National Laboratory, Argonne, IL 60439 (United States); Benmore, C.J. [Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Physics, Arizona State University, AZ 85287 (United States); Tailor, A.N.; Tumber, S.K. [Materials Development, Inc., Arlington Heights, IL 60004 (United States); Neuefeind, J. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Cherry, B. [Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Yarger, J.L. [Department of Physics, Arizona State University, AZ 85287 (United States); Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Mou, Q. [Magnetic Resonance Research Center, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Weber, W. [Department of Physics, Arizona State University, AZ 85287 (United States); Department of Chemistry and Biochemistry, Arizona State University, AZ 85287 (United States); Byrn, S.R. [Department of Industrial and Physical Pharmacy, Purdue University, IN 47907 (United States)

    2013-10-16

    Highlights: • Acoustic levitation was used to make phase-pure glassy forms of pharmaceutical compounds. • Neutrons, X-rays and NMR were used to characterize the glasses. • The glass comprised of slightly distorted molecules packed in a random network. • Potential for new drug synthesis routes is discussed. - Abstract: Acoustic levitation was used to trap 1–3 mm diameter drops of Probucol and other pharmaceutical materials in containerless conditions. Samples were studied in situ using X-ray diffraction and ex situ using neutron diffraction, NMR and DSC techniques. The materials were brought into non-equilibrium states by supersaturating solutions or by supercooling melts. The glass transition and crystallization temperatures of glassy Probucol were 29 ± 1 and 71 ± 1 °C respectively. The glassy form was stable with a shelf life of at least 8 months. A neutron/X-ray difference function of the glass showed that while molecular sub-groups remain rigid, many of the hydrogen correlations observed in the crystal become smeared out in the disordered material. The glass is principally comprised of slightly distorted Form I Probucol molecules with disordered packing rather than large changes in the individual molecular structure. Avoiding surface contact-induced nucleation provided access to highly non-equilibrium phases and enabled synthesis of phase-pure glasses.

  10. 1H MAS and 1H --> 31P CP/MAS NMR study of human bone mineral.

    Science.gov (United States)

    Kaflak-Hachulska, A; Samoson, A; Kolodziejski, W

    2003-11-01

    Chemical structure of human bone mineral was studied by solid-state nuclear magnetic resonance (NMR) with magic-angle spinning (MAS). Trabecular and cortical bone samples from adult subjects were compared with mineral standards: hydroxyapatite (HA), hydrated and calcined, carbonatoapatite of type B with 9 wt% of CO3(2-) (CHA-B), brushite (BRU) and mixtures of HA with BRU. Proton spectra were acquired with excellent spectral resolution provided by ultra-high speed MAS at 40 kHz. 2D 1H-31P NMR heteronuclear correlation was achieved by cross-polarization (CP) under fast MAS at 12 kHz. 31P NMR was applied with CP from protons under slow MAS at 1 kHz. Appearance of 31P rotational sidebands together with their CP kinetics were analyzed. It was suggested that the sidebands of CP spectra are particularly suitable for monitoring the state of apatite crystal surfaces. The bone samples appeared to be deficient in structural hydroxyl groups analogous to those in HA. We found no direct evidence that the HPO4(2-) brushite-like ions are present in bone mineral. The latter problem is extensively discussed in the literature. The study proves there is a similarity between CHA-B and bone mineral expressed by their similar NMR behavior.

  11. STRUCTURAL STUDIES OF BIOMATERIALS USING DOUBLE-QUANTUM SOLID-STATE NMR SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Drobny, Gary P.; Long, J. R.; Karlsson, T.; Shaw, Wendy J.; Popham, Jennifer M.; Oyler, N.; Bower, Paula M.; Stringer, J.; Gregory, D.; Mehta, M.; Stayton, Patrick S.

    2004-10-31

    Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composites technologies. Here, we describe both the theory and practice of double-quantum solid-stateNMR(ssNMR) structure-determination techniques, as they are used to determine the secondary structures of surface-adsorbed peptides and proteins. In particular, we have used ssNMR dipolar techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxyapatite (HAP) surface. Here, we also review NMR data on peptides designed to adsorb from aqueous solutions onto highly porous hydrophobic surfaces with specific helical secondary structures. The adsorption or covalent attachment of biological macromolecules onto polymer materials to improve their biocompatibility has been pursued using a variety of approaches, but key to understanding their efficacy is the verification of the structure and dynamics of the immobilized biomolecules using double-quantum ssNMR spectroscopy.

  12. NMR structural studies of oligosaccharides and other natural products

    DEFF Research Database (Denmark)

    Kjærulff, Louise

    produce secondary metabolites for signaling and competing against other organisms, and these molecules are important in drug discovery due to their inherent biological activities. From a marine Photobacterium (P. halotolerans) we isolated the solonamides and the ngercheumicins, two families of cyclic....... fijiensis, was also investigated for production of novel secondary metabolites, and a new pyranonigrin (E) was isolated and structure elucidated by NMR spectroscopy along with JBIR-74 and decumbenone A, two known metabolites previously isolated from Aspergillus and Penicillium species. Oligosaccharides...... with respect to n+1JHH between these two experiments, observed in the nJCH HMBC cross peak. Through a double editing procedure this enables straightforward determination of both sign and magnitude of n+1JHH, including for very small coupling constants. Excellent results were obtained for the natural product...

  13. NMR studies of alkali C{sub 60} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Stenger, V.A.; Recchia, C.; Pennington, C.H. [Ohio State Univ., Columbus, OH (United States)] [and others

    1994-12-01

    The authors report {sup 13}C, {sup 87}Rb, {sup 39}K, and {sup 133}Cs nuclear magnetic resonance (NMR) measurements of lineshapes, Knight shifts, and spin-lattice relaxation rates in the normal and superconducting states of M{sub 3}C{sub 60}, where M{sub 3} = Rb{sub 3}, K{sub 3}, Rb{sub 2}K, RbK{sub 2}, Rb{sub 2}Cs, and RbCs{sub 2}. Measurements are used as a guide to a new ammonia solvent synthesis technique. Temperature dependence of the superconducting state electron spin susceptibility is found to follow BCS weak coupling predictions. The issue of the Hebel-Slichter coherence peak is addressed.

  14. Molecular dynamics of solid cortisol studied by NMR

    Science.gov (United States)

    Andrew, E. R.

    Polycrystalline cortisol (hydrocortisone; 11β,17α,21-trihydroxy-4-preg- nene-3,20-dione; C21H30O5) has been investigated by continuous and pulse proton NMR methods between 78 and 400 K at Larmor frequencies of 7, 25 and 60 MHz. A reduced value of second moment was found above 90 K and is ascribed to reorientation of two methyl groups. A single asymmetric minimum was found in the temperature dependence of the spin-lattice relaxation times and this also is attributed to reorientation of two methyl groups. The asymmetry suggests an asymmetric distribution of correlation times of the motion. Using the Cole-Davidson distribution, the best computer fit yields the following parameters characterizing the motion: Ea = 11ṡ8 ± 0ṡ1 kJ mol-1, τ0 = 4ṡ6 ± 0ṡ4) x 10-13s, distribution parameter δ = 0ṡ62.

  15. NMR study of size effects in relaxor PMN nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Blinc, Robert [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Zalar, Bostjan; Zupancic, Blaz [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); EN-FIST Centre of Excellence, Dunajska cesta 156, 1000 Ljubljana (Slovenia); Morozovska, Anna N. [Institute for Problems of Material Science, National Academy of Sciences of Ukraine, Krjijanovskogo 3, 03142 Kiev (Ukraine); V. Lashkarev Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, prospekt Nauki 41, 03028 Kiev (Ukraine); Glinchuk, Maya D. [Institute for Problems of Material Science, National Academy of Sciences of Ukraine, Krjijanovskogo 3, 03142 Kiev (Ukraine)

    2011-11-15

    {sup 93}Nb 1/2{yields} -1/2 NMR line shape and spin-lattice measurements show that microcrystalline PbMg{sub 1/3}Nb{sub 2/3}O{sub 3} (PMN) powder is dynamically disordered at room temperature, whereas nanocrystalline PMN powder is orientationally frozen out and long-range ordered at room temperature. The dynamical disorder of the microcrystalline powder results in a motional averaging of the anisotropic part of the {sup 93}Nb chemical shift tensor and second order quadrupole shift, whereas this averaging is absent in the nanocrystalline powder, resulting in a broader central line and a longer spin-lattice relaxation time. This seems to be the first observation of such size effects in a relaxor. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. One new and six known triterpene xylosides from Cimicifuga racemosa: FT-IR, Raman and NMR studies and DFT calculations

    Science.gov (United States)

    Jamróz, Marta K.; Jamróz, Michał H.; Cz. Dobrowolski, Jan; Gliński, Jan A.; Gleńsk, Michał

    One new and six known triterpene xylosides were isolated from Cimicifuga racemosa (black cohosh, Actaea racemosa). The structure of a new compound, designated as isocimipodocarpaside (1), was established to be (24S)-3β-hydroxy-24,25-oxiirane-16,23-dione-9,10-seco-9,19-cyclolanost-1(10),7(8),9(11)-trien 3-O-β-D-xylopyranoside, by means of 1H and 13C NMR, IR and Raman spectroscopies and Mass Spectrometry. The six known compounds are: 23-epi-26-deoxycimicifugoside (2), 23-epi-26-deoxyactein (3), 25-anhydrocimigenol xyloside (4), 23-O-acetylshengmanol xyloside (5), 25-O-acetylcimigenol xyloside (6) and 3'-O-acetylcimicifugoside H-1 (7). On the basis of NMR data supported by DFT calculations of NMR shielding constants of (2), its structure, previously described as 26-deoxycimicifugoside was corrected and determined as 23-epi-26-deoxycimicifugoside. The 13C CPMAS NMR spectra of the studied compounds (1)-(7) provided data on their solid-state interactions. The IR and Raman spectra in the Cdbnd O, Cdbnd C, and Csbnd H stretching vibration regions clearly discriminate different triterpenes found in C. racemosa.

  17. NMR studies of a new family of DNA binding proteins: the THAP proteins

    Energy Technology Data Exchange (ETDEWEB)

    Gervais, Virginie, E-mail: virginie.gervais@ipbs.fr [IPBS (Institut de Pharmacologie et de Biologie Structurale), CNRS (France); Campagne, Sebastien [ETH Zurich (Switzerland); Durand, Jade; Muller, Isabelle; Milon, Alain, E-mail: alain.milon@ipbs.fr [IPBS (Institut de Pharmacologie et de Biologie Structurale), CNRS (France)

    2013-05-15

    The THAP (THanatos-Associated Protein) domain is an evolutionary conserved C2CH zinc-coordinating domain shared with a large family of cellular factors (THAP proteins). Many members of the THAP family act as transcription factors that control cell proliferation, cell cycle progression, angiogenesis, apoptosis and epigenetic gene silencing. They recognize specific DNA sequences in the promoters of target genes and subsequently recruit effector proteins. Recent structural and functional studies have allowed getting better insight into the nuclear and cellular functions of some THAP members and the molecular mechanisms by which they recognize DNA. The present article reviews recent advances in the knowledge of the THAP domains structures and their interaction with DNA, with a particular focus on NMR. It provides the solution structure of the THAP domain of THAP11, a recently characterized human THAP protein with important functions in transcription and cell growth in colon cancer.

  18. Solid state NMR method development and studies of biological and biomimetic nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yanyan [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    This thesis describes application and development of advanced solid-state nuclear magnetic resonance techniques for complex materials, in particular organic-inorganic nanocomposites and thermoelectric tellurides. The apatite-collagen interface, essential for understanding the biomineralization process in bone and engineering the interface for controlled bio-mimetic synthesis and optimized mechanical properties, is buried within the nanocomposite of bone. We used multinuclear solid-state NMR to study the composition and structure of the interface. Citrate has been identified as the main organic molecule strongly bound to the apatite surface with a density of 1/(2 nm)2, covering 1/6 of the total surface area in bovine bone. Citrate provides more carboxylate groups, one of the key functional groups found to affect apatite nucleation and growth, than all the non-collagenous proteins all together in bone; thus we propose that citrate stabilizes apatite crystals at a very small thickness of ~3 nm (4 unit cells) to increase bone fracture tolerance. The hypothesis has been confirmed in vitro by adding citrate in the bio-mimetic synthesis of polymerhydroxyapatite nanocomposites. The results have shown that the size of hydroxyapatite nanocrystals decreases as increasing citrate concentration. With citrate concentrations comparable to that in body fluids, similar-sized nanocrystals as in bone have been produced. Besides the dimensions of the apatite crystals, the composition of bone also affects its biofunctional and macroscopic mechanical properties; therefore, our team also extended its effort to enhance the inorganic portion in our bio-mimetic synthesis from originally 15 wt% to current 50 wt% compared to 65 wt% in bovine bone, by using Lysine-Leucine hydroxyapatite nucleating diblock co-polypeptide, which forms a gel at very low concentration. In this thesis, various advanced solid state NMR techniques have been employed to characterize nanocomposites

  19. NMR relaxometry study of plaster mortar with polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Jumate, E.; Manea, D. [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania); Moldovan, D.; Fechete, R. [Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca (Romania)

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

  20. NMR study of magnetic fluctuations in 115 actinide compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kambe, S. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan)]. E-mail: kambe.shinsaku@jaea.go.jp; Sakai, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Tokunaga, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Kato, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Fujimoto, T. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Walstedt, R.E. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Ikeda, S. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Matsuda, T.D. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Haga, Y. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Aoki, D. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Homma, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Shiokawa, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Onuki, Y. [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2007-03-15

    We report NMR measurements in isostructural compounds (HoCoGa{sub 5}: 115 type) AnTGa{sub 5} (An: U, Np and Pu, T: Fe, Co and Pt) with different ground states (paramagnet, antiferromagnet and superconductor) using single crystal samples. The electrical field gradient at the Ga and Co sites are similar in all compounds, indicating that the charge distribution around these sites is determined mainly by intra-atomic orbitals. In contrast, the hyperfine coupling constants at the Ga and Co sites depend on the compounds considerably. Since the hyperfine coupling at the ligand sites is a transferred hyperfine coupling due to hybridization between 5f and ligand orbitals, it is natural that the hyperfine coupling constant depends on the 5f electronic states. Spin-lattice relaxation rates (1/T{sub 1}) in the paramagnetic state show more drastic differences between the compounds. In the antiferromagnets UPtGa{sub 5}, NpFeGa{sub 5} and NpCoGa{sub 5}, 1/T{sub 1}T shows a Curie-Weiss behavior at high temperatures, indicating a strong localized character. By contrast, in the paramagnet UFeGa{sub 5}1/T{sub 1}T is small and almost independent of T, indicating an ordinary metallic state with weak exchange enhancement. Finally, in the superconductor PuRhGa{sub 5} the magnitude of 1/T{sub 1}T lies between those of the antiferromagnets and the paramagnet.

  1. SYNTHESIS, INFRARED AND NMR STUDIES OF SOME SULFATO DIORGANOSTANNIC DERIVATIVES

    Directory of Open Access Journals (Sweden)

    DAOUDA NDOYE

    2014-08-01

    Full Text Available EthylendiammoniumSO4•SnBu2Cl2•1/4ethylendiammoniumCl2 (A, 2ethylendiammoniumSO4•SnBu2Cl2 (B and Cy2NH2SO4H•Cy2NH2SnBu2Cl3 (C complexes have been obtained on allowing ethylendiammoniumSO4 and Cy2NH2HSO4 to react respectively with SnBu2Cl2 in specific ratios. The molecular structures of these compounds have been determined on the basis of infrared and NMR data. The suggested structures are dimeric and tetrameric, the tin atom being hexacoordinated, the sulphate anions behaving as a monochelating ligand or non-coordinating and only involved in hydrogen bonds. The hydrogenosulfate is a non-sigma coordinating anion but only involved in hydrogen bonds of acetic acid type or NH…O bonds. The presence of dimeric [(SnBu2Cl32]2- in one of the structures is noteworthy. The key role of the cations involved in hydrogen bonds is outlined.

  2. Italian and Argentine olive oils: a NMR and gas chromatographic study

    Directory of Open Access Journals (Sweden)

    Segre, Annalaura

    2001-12-01

    Full Text Available High-field Nuclear Magnetic Resonance (NMR spectroscopy and Gas Chromatography (GC were used to analyze 16 monovarietal olive oils obtained from few matched Mediterranean cultivars grown in experimental fields located in Italy and in the Catamarca region of Argentina. The Catamarca region is characterized by extreme pedoclimatic conditions and by a wild spontaneous vegetation. The proposed sampling allows to study the effect of different pedoclimatic conditions on olive oil composition. GC gives the fatty acid profile of olive oil samples. 1H and 13C NMR techniques provide different information: the 1H NMR spectrum allows the measurement of minor components of olive oils such as b-sytosterol, hexanal, trans-2-hexenal, formaldehyde, squalene, cycloartenol and linolenic acid; the 1C NMR spectrum allows to obtain information about glycerol tri-esters of olive oils, i.e., about their acyl composition and positional distribution on glycerol moiety. All the NMR and GC results have been submitted to Linear Discriminant Analysis (LDA and Tree Cluster Analysis (TCA. A careful analysis of the statistical results allows to select the Mediterranean cultivars less affected by the climatic conditions present in the Catamarca region. The selected cultivars produce olive oils which keep their Mediterranean characteristics and which can be proposed as colonizing plants in this wild Argentine region.La espectroscopía de Resonancia Magnética Nuclear de alta resolución (RMN y Cromatografía Gaseosa (CG fueron utilizadas para analizar 16 monovariedades de aceites de oliva, obtenidas de algunos olivares Mediterráneos cultivados contemporáneamente en campos experimentales localizados en Italia y en la región de Catamarca en Argentina. Estas muestras permiten estudiar diferentes condiciones pedoclimáticas en la composición de los aceite de oliva. La CG proporciona el perfil en ácidos grasos de los aceites de oliva y las técnicas RMN 1H y RMN 13C suministran

  3. Methyl quantum tunneling and nitrogen-14 NQR NMR studies using a SQUID magnetic resonance spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Black, Bruce Elmer [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1993-07-01

    Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) techniques have been very successful in obtaining molecular conformation and dynamics information. Unfortunately, standard NMR and NQR spectrometers are unable to adequately detect resonances below a few megahertz due to the frequency dependent sensitivity of their Faraday coil detectors. For this reason a new spectrometer with a dc SQUID (Superconducting Quantum Interference Device) detector, which has no such frequency dependence, has been developed. Previously, this spectrometer was used to observe 11B and 27Al NQR resonances. The scope of this study was increased to include 23Na, 51V, and 55Mn NQR transitions. Also, a technique was presented to observe 14N NQR resonances through cross relaxation of the nitrogen polarization to adjacent proton spins. When the proton Zeeman splitting matches one nitrogen quadrupoler transition the remaining two 14N transitions can be detected by sweeping a saturating rf field through resonance. Additionally, simultaneous excitation of two nitrogen resonances provides signal enhancement which helps to connect transitions from the same site. In this way, nitrogen-14 resonances were observed in several amino acids and polypeptides. This spectrometer has also been useful in the direct detection of methyl quantum tunneling splittings at 4.2 K. Tunneling, frequencies of a homologous series of carboxylic acids were measured and for solids with equivalent crystal structures, an exponential correlation between the tunneling frequency and the enthalpy of fusion is observed. This correlation provides information about the contribution of intermolecular interactions to the energy barrier for methyl rotation.

  4. Solid-state NMR studies of bacteriorhodopsin and the purple membrane

    CERN Document Server

    Mason, A J

    2001-01-01

    proteins. This technique may prove particularly useful when studying large proteins that are difficult to orient where the MAS lineshapes will remain relatively unaffected in comparison with current static NMR methods. Finally the MAOSS method was extended to the study of the lipid components of the purple membrane and the feasibility of determining structural constraints from phospholipid headgroups was assessed. The potential of using sup 3 sup 1 P NMR to observe qualitative protein-lipid interactions in both the purple membrane and reconstituted membranes containing bovine rhodopsin was also demonstrated. Following the demonstration of a new MAS NMR method for resolving orientational constraints in uni-axially oriented biological membranes (Glaubitz and Watts, 1998), experiments were performed to realise the potential of the new method on large, oriented membrane proteins. Using bacteriorhodopsin in the purple membrane as a paradigm for large membrane proteins, the protein was specifically labelled with de...

  5. Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin.

    Science.gov (United States)

    Wałęsa, Roksana; Ptak, Tomasz; Siodłak, Dawid; Kupka, Teobald; Broda, Małgorzata A

    2014-06-01

    The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by (1)H and (13)C NMR. Six complexes EYL-Ac-Phe-NHMe, stabilized by N-H···O or/and C-H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar 'head' of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in phosphate group that acts as proton acceptor. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Synergistic Applications of MD and NMR for the Study of Biological Systems

    Directory of Open Access Journals (Sweden)

    Olivier Fisette

    2012-01-01

    same time, theoretical and computational approaches gain in reliability and their field of application widens. In this short paper, we discuss recent advances in the areas of solution nuclear magnetic resonance (NMR spectroscopy and molecular dynamics (MD simulations that were made possible by the combination of both methods, that is, through their synergistic use. We present the main NMR observables and parameters that can be computed from simulations, and how they are used in a variety of complementary applications, including dynamics studies, model-free analysis, force field validation, and structural studies.

  7. Dynamic NMR study of dinitrophenyl derivatives of seven-membered cyclic ketals of pyridoxine.

    Science.gov (United States)

    Rakhmatullin, Ilfat Z; Galiullina, Leisan F; Garipov, Marsel' R; Strel'nik, Alexey D; Shtyrlin, Yurii G; Klochkov, Vladimir V

    2015-10-01

    Two pyridoxine derivatives containing a dinitrophenyl moiety were investigated by (1)H NMR spectroscopy. Conformational dynamics in solution were studied for each compound using dynamic NMR experiments. It was shown that both compounds studied are involved into two conformational exchange processes. The first process is a transformation of the seven-membered cycle conformation between the enantiomeric P-twist and M-twist forms, and the second is a rotation of the dinitrophenyl fragment of the molecules around the C-O bond. Energy barriers of both conformational transitions were determined.

  8. 31p NMR and ESI-MS Studies on Some Intermediates of the Peptide Coupling Reagents Triphenyl-chlorophosphoranes

    Institute of Scientific and Technical Information of China (English)

    Guo TANG; Gui Ji ZHOU; Feng NI; Li Ming HU; Yu Fen ZHAO

    2005-01-01

    The intermediates of the Appel coupling reagents were studied in acetonitrile,dimethoxyethane and dioxane by 31P NMR, C NMR spectrum and ESI-MS. In dioxane a new high coordinated phosphorous compound with 31p NMR shift at -39 ppm was observed. The ESI-MS showed that it could be a penta-coordinated phosphorous compound containing dioxane. The carboxyl activated intermediates were also studied in three solvents.

  9. STUDIES ON THE CHEMICAL STRUCTURES OF ACTIVATED CARBON FIBERS BY SOLID STATE NMR

    Institute of Scientific and Technical Information of China (English)

    FURuowen; HuangWenqiang; 等

    1999-01-01

    The solid state C13-NMR spectra of different ACFs from various precursor fibers were recorded in this paper,The effects of activation conditions on chemical structures of ACFs,as well as the changes of chemical structures during carbonization and redox reaction were inverstigated by NMR technique,At same time,the soild state P31-NMR spectra of ACFS are studied.The C13-NMR spectra of ACFs can be divided into six bands that are assigned to methyl and methylene groups,hydroxyl and ether groups.acetal (or methylenedioxy) carbon,graphite-like aromatic carbon structure,phenol,and quinone groups,respectively.Only phosphorous pentoxide exists on ACFs and CFs.Moreover,most of them are stuck over the crystal face but not at the edge of graphite-like micro-crystal.The carbonization and activation conditions affect the C13-NMR spectra of ACFs.The experimental rsults indicate that the redox reaction of ACFs with oxidants greatly consumes C-H group.

  10. An in-cell NMR study of monitoring stress-induced increase of cytosolic Ca2+ concentration in HeLa cells.

    Science.gov (United States)

    Hembram, Dambarudhar Shiba Sankar; Haremaki, Takahiro; Hamatsu, Jumpei; Inoue, Jin; Kamoshida, Hajime; Ikeya, Teppei; Mishima, Masaki; Mikawa, Tsutomu; Hayashi, Nobuhiro; Shirakawa, Masahiro; Ito, Yutaka

    2013-09-06

    Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. The lifetime of in-cell NMR samples is however much shorter than that in culture media, presumably because of various stresses as well as the nutrient depletion in the anaerobic environment within the NMR tube. It is well known that Ca(2+)-bursts occur in HeLa cells under various stresses, hence the cytosolic Ca(2+) concentration can be regarded as a good indicator of the healthiness of cells in NMR tubes. In this study, aiming at monitoring the states of proteins resulting from the change of cytosolic Ca(2+) concentration during experiments, human calbindin D9k (P47M+C80) was used as the model protein and cultured HeLa cells as host cells. Time-resolved measurements of 2D (1)H-(15)N SOFAST-HMQC experiments of calbindin D9k (P47M+C80) in HeLa cells showed time-dependent changes in the cross-peak patterns in the spectra. Comparison with in vitro assignments revealed that calbindin D9k (P47M+C80) is initially in the Mg(2+)-bound state, and then gradually converted to the Ca(2+)-bound state. This conversion process initiates after NMR sample preparation. These results showed, for the first time, that cells inside the NMR tube were stressed, presumably because of cell precipitation, the lack of oxygen and nutrients, etc., thereby releasing Ca(2+) into cytosol during the measurements. The results demonstrated that in-cell NMR can monitor the state transitions of stimulated cells through the observation of proteins involved in the intracellular signalling systems. Our method provides a very useful tool for in situ monitoring of the "healthiness" of the cells in various in-cell NMR studies.

  11. Anomalous diffusion of Ibuprofen in cyclodextrin nanosponge hydrogels: an HRMAS NMR study

    Directory of Open Access Journals (Sweden)

    Monica Ferro

    2014-11-01

    Full Text Available Ibuprofen sodium salt (IP was encapsulated in cyclodextrin nanosponges (CDNS obtained by cross-linking of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn in two different preparations: CDNSEDTA 1:4 and 1:8, where the 1:n notation indicates the CD to EDTAn molar ratio. The entrapment of IP was achieved by swelling the two polymers with a 0.27 M solution of IP in D2O, leading to colourless, homogeneous hydrogels loaded with IP. The molecular environment and the transport properties of IP in the hydrogels were studied by high resolution magic angle spinning (HRMAS NMR spectroscopy. The mean square displacement (MSD of IP in the gels was obtained by a pulsed field gradient spin echo (PGSE NMR pulse sequence at different observation times td. The MSD is proportional to the observation time elevated to a scaling factor α. The α values define the normal Gaussian random motion (α = 1, or the anomalous diffusion (α 1 superdiffusion. The experimental data here reported point out that IP undergoes subdiffusive regime in CDNSEDTA 1:4, while a slightly superdiffusive behaviour is observed in CDNSEDTA 1:8. The transition between the two dynamic regimes is triggered by the polymer structure. CDNSEDTA 1:4 is characterized by a nanoporous structure able to induce confinement effects on IP, thus causing subdiffusive random motion. CDNSEDTA 1:8 is characterized not only by nanopores, but also by dangling EDTA groups ending with ionized COO− groups. The negative potential provided by such groups to the polymer backbone is responsible for the acceleration effects on the IP anion thus leading to the superdiffusive behaviour observed. These results point out that HRMAS NMR spectroscopy is a powerful direct method for the assessment of the transport properties of a drug encapsulated in polymeric scaffolds. The diffusion properties of IP in CDNS can be modulated by suitable polymer synthesis; this finding opens the possibility to design

  12. Impact of opal nanoconfinement on electronic properties of sodium particles: NMR studies

    Energy Technology Data Exchange (ETDEWEB)

    Charnaya, E.V., E-mail: charnaya@live.com [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Institute of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Lee, M.K. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); MoST Instrument Center at NCKU, Tainan, 70101 Taiwan (China); Chang, L.J. [Department of Physics, National Cheng Kung University, Tainan, 70101 Taiwan (China); Kumzerov, Yu.A.; Fokin, A.V. [A.F. Ioffe Physico-Technical Institute RAS, St. Petersburg, 194021 (Russian Federation); Samoylovich, M.I. [Moscow Institute of Physics and Technology, Moscow, 141700 (Russian Federation); Bugaev, A.S. [CSR Institute of Technology “Technomash”, Moscow, 121108 (Russian Federation)

    2015-03-20

    The {sup 23}Na Knight shift of NMR line which is highly correlated with the electron spin susceptibility and density of states at the Fermi level was studied for the sodium loaded opal. The measurements were carried out within a temperature range from 100 to 400 K for solid and melted confined sodium nanoparticles. The NMR line below 305 K was a singlet with the Knight shift reduced compared to that in bulk. Above this temperature the NMR line split reproducibly into two components with opposite trends in the Knight shift temperature dependences which evidenced a nanoconfinement-induced transformation and heterogeneity in the electron system. The findings were suggested to be related to changes in the topology of the Fermi surface.

  13. 125Te and 139La NMR Studies of Single Crystal LaTe3

    Science.gov (United States)

    Chudo, Hiroyuki; Michioka, Chishiro; Itoh, Yutaka; Yoshimura, Kazuyoshi

    2007-12-01

    We report 125Te and 139La NMR studies for single crystals of LaTe3 between 10 and 160 K under an applied field of H = 7.4841 T. We observed the broad 125Te(1) NMR signals of metallic Te(1) sheets with a superlattice modulation and the sharp 125Te(2) and 139La NMR signals of LaTe(2) bi-layers. Temperature dependence of 125Te(1) nuclear spin-lattice relaxation times of the modulated Te(1) sheets obeys a modified Korringa relation. The results indicate that the electronic state on the Te(1) sheets is a Landau-Fermi liquid on a misfit superlattice or a Tomonaga-Luttinger liquid in a two-dimensional charge-density wave ordering state.

  14. NMR and Infrared Study of Thermal Oxidation of cis-1, 4-Polybutadiene

    Science.gov (United States)

    Gemmer, Robert V.; Golub, Morton A.

    1978-01-01

    A study of the microstructural changes occuring in CB during thermal, uncatalyzed oxidation was carried out. Although the oxidation of CB is accompanied by extensive crosslinking with attendant insolubilization, it was found possible to follow the oxidation of solid CB directly with C-13 NMR spectroscopy. The predominant products appearing in the C-13 NMR spectra of oxidized CB are epoxides. The presence of lesser amounts of alcohols, peroxides, and carbonyl structures was adduced from complementary infrared and NMR spectra of soluble extracts obtained from the oxidized, crosslinked CB. This distribution of functional groups contrasts with that previously reported for the autooxidation of 1,4-polyisoprene. The difference was rationalized in terms of the relative stabilities of intermediate radical species involved in the autoxidation of CB and 1,4-polyisoprene.

  15. High-temperature NMR study of zeolite Na-A: Detection of a phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, R.; Tijink, G.A.H.; Veeman, W.S.; Maesen, T.L.M.; van Lent, J.F. (Univ. of Nijmegen (Netherlands))

    1989-01-26

    The zeolite Linde 4A is studied by {sup 23}Na, {sup 27}al, and {sup 29}Si NMR at temperatures up to 953 K. {sup 23}Na NMR shows that the quadrupole interaction of sodium ions sited at 6-rings decreases when the temperature increases. With the aid of two-dimensional nutation and exchange experiments it can be shown that large-amplitude motions of the sodium ions, which in principle could explain a decrease of quadrupole interactions, do not occur. The decrease of the quadrupole interaction can be interpreted in terms of a phase transition. From a comparison of the NMR spectra of {sup 23}Na and {sup 27}Al it is concluded that the zeolite framework undergoes a major structural change upon increasing the temperature, before the sodium ions are displaced at higher temperatures. The exchange of sodium ions for potassium ions shifts this transition to higher temperatures.

  16. A combination of novel solid-state NMR methods and related software to study molecular assemblies and biomolecules

    NARCIS (Netherlands)

    Gradmann, S.H.E.

    2013-01-01

    Solid-state Nuclear Magnetic Resonance (ssNMR) is a versatile spectroscopic method that can be applied to various samples relevant in life and material science and provides atomic insight into molecular structure, dynamics and assembly. The present thesis describes the diversity and utility of ssNMR

  17. Study of the cardiotoxicity of Venenum Bufonis in rats using an 1H NMR-based metabolomics approach.

    Directory of Open Access Journals (Sweden)

    Ge Dong

    Full Text Available Venenum Bufonis, a well-known traditional Chinese medicine, has been widely used in Asia and has gained popularity in Western countries over the last decade. Venenum Bufonis has obvious side effects that have been observed in clinical settings, but few studies have reported on its cardiotoxicity. In this work, the cardiotoxicity of Venenum Bufonis was investigated using a 11H NMR-based metabolomics approach. The 1H NMR profiles of the serum, myocardial extracts and liver extracts of specific-pathogen-free rats showed that Venenum Bufonis produced significant metabolic perturbations dose-dependently with a distinct time effect, peaking at 2 hr after dosing and attenuating gradually. Clinical chemistry, electrocardiographic recordings, and histopathological evaluation provided additional evidence of Venenum Bufonis-induced cardiac damage that complemented and supported the metabolomics findings. The combined results demonstrated that oxidative stress, mitochondrial dysfunction, and energy metabolism perturbations were associated with the cardiac damage that results from Venenum Bufonis.

  18. Studies on the Interactions between Potassium oxalato oxodiperoxovanadate and Histidine by NMR and MS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Multi-nuclear NMR and ESI-MS have been applied to study the interactions between oxalato-oxodiperoxovanadate and histidine in neutral solution. Coordination between the complex and histidine was monitored by 51V NMR. A pair of new isomers produced via vanadium atom binding separately to N1 and N3 of the imidazole ring of histidine was characterized by several spectroscopic methods. Experimental results show that the structure activity relationship of peroxovanadium complexes bearing organic ligands may be related to the specific recognition between peroxovanadium and histidine residue of tyrosine phosphatase.

  19. NMR and IR Studies on Eight Complexes of Eu with Three Kinds of Ligands

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Eight binary and ternary solid complexes of Eu3+ with pyridine-2, 6-dicarboxylic acid (H2DPC), 1,10-phen-anthroline (phen) and methylbenzoic acid (MBA), including o-MBA, m-MBA and p-MBA, were synthesised. Their compositions were confirmed by elemental analysis. The coordination mode of ligands with Eu3+ was studied by NMR and IR. The coordination number of eight complexes was also investigated. Furthermore, the influence on chemical shift and NMR spectrum shape by induction effect, screening effect and paramagnetic character of Eu3+ were discussed in detail.

  20. Lithium substitution in strontium chlorapatite studied by solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, S.; Sairam, T. N., E-mail: sai@igcar.gov.in; Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Maji, B. K.; Jena, H. [Chemical Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2016-05-23

    Strontium Chlorapatites with various amounts of Li substitution (Sr{sub 10-x}Li{sub x}(PO{sub 4}){sub 6}Cl{sub 2-δ}) were prepared by solid state reaction method and characterized by powder XRD and solid state NMR spectroscopy. XRD reveals shortening of lattice parameters upon Li incorporation. The linewidth of {sup 31}P solid state Magic Angle Spinning NMR spectra decreases with increase in Li content within the apatite phase. This study confirms Li uptake within the apatite phase.

  1. Variable temperature NMR studies on the conformations of tonalensin in solution

    Science.gov (United States)

    Ortega, Alfredo; Maldonado, Emma; Díaz, Eduardo; Reynolds, William F.

    1998-05-01

    NMR studies on tonalensin 1, a diterpene containing a ten membered ring, made evident the presence of three conformational isomers in solution. At room temperature compound 1 exists as a mixture of the conformers 1A and 1B in a ratio 1:1 in a CDC1 3 solution and 1.5:1 in a Me 2CO-d 6/DMSO-d 6 solution. At lower temperatures a third conformer, 1C, was detected. It was responsible for the line broadening observed for 1A. Temperature dependent 2D NMR experiments have been employed to elucidate the automerization of compound 1.

  2. {sup 11}B-NMR spectroscopic study on the interaction of epinephrine and p-BPA

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, K.; Yoshino, K. [Shinshu Univ., Department of Chemistry, Matsumoto, Nagano (Japan)

    2000-10-01

    It is studied that p-BPA (p-bronophenylalanine) which formed complex with catechol functional group has interaction with epinephrine by {sup 11}B-NMR. Two {sup 11}B-NMR resonance signals were observed at pH 7.0. The signal at 29.6 ppm is assigned to p-BPA and at 10.8 ppm is assigned to that of complex. We can determine complex formation constants (logK') in various pH. (author)

  3. Altered metabolism of growth hormone receptor mutant mice: a combined NMR metabonomics and microarray study.

    Directory of Open Access Journals (Sweden)

    Horst Joachim Schirra

    Full Text Available BACKGROUND: Growth hormone is an important regulator of post-natal growth and metabolism. We have investigated the metabolic consequences of altered growth hormone signalling in mutant mice that have truncations at position 569 and 391 of the intracellular domain of the growth hormone receptor, and thus exhibit either low (around 30% maximum or no growth hormone-dependent STAT5 signalling respectively. These mutations result in altered liver metabolism, obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: The analysis of metabolic changes was performed using microarray analysis of liver tissue and NMR metabonomics of urine and liver tissue. Data were analyzed using multivariate statistics and Gene Ontology tools. The metabolic profiles characteristic for each of the two mutant groups and wild-type mice were identified with NMR metabonomics. We found decreased urinary levels of taurine, citrate and 2-oxoglutarate, and increased levels of trimethylamine, creatine and creatinine when compared to wild-type mice. These results indicate significant changes in lipid and choline metabolism, and were coupled with increased fat deposition, leading to obesity. The microarray analysis identified changes in expression of metabolic enzymes correlating with alterations in metabolite concentration both in urine and liver. Similarity of mutant 569 to the wild-type was seen in young mice, but the pattern of metabolites shifted to that of the 391 mutant as the 569 mice became obese after six months age. CONCLUSIONS/SIGNIFICANCE: The metabonomic observations were consistent with the parallel analysis of gene expression and pathway mapping using microarray data, identifying metabolites and gene transcripts involved in hepatic metabolism, especially for taurine, choline and creatinine metabolism. The systems biology approach applied in this study provides a coherent picture of metabolic changes resulting from impaired STAT5 signalling by the growth hormone

  4. Solvent dynamical behavior in an organogel phase as studied by NMR relaxation and diffusion experiments.

    Science.gov (United States)

    Yemloul, Mehdi; Steiner, Emilie; Robert, Anthony; Bouguet-Bonnet, Sabine; Allix, Florent; Jamart-Grégoire, Brigitte; Canet, Daniel

    2011-03-24

    An organogelation process depends on the gelator-solvent pair. This study deals with the solvent dynamics once the gelation process is completed. The first approach used is relaxometry, i.e., the measurement of toluene proton longitudinal relaxation time T(1) as a function of the proton NMR resonance frequency (here in the 5 kHz to 400 MHz range). Pure toluene exhibits an unexpected T(1) variation, which has been identified as paramagnetic relaxation resulting from an interaction of toluene with dissolved oxygen. In the gel phase, this contribution is retrieved with, in addition, a strong decay at low frequencies assigned to toluene molecules within the gel fibers. Comparison of dispersion curves of pure toluene and toluene in the gel phase leads to an estimate of the proportion of toluene embedded within the organogel (found around 40%). The second approach is based on carbon-13 T(1) and nuclear Overhauser effect measurements, the combination of these two parameters providing direct information about the reorientation of C-H bonds. It appears clearly that reorientation of toluene is the same in pure liquid and in the gel phase. The only noticeable changes in carbon-13 longitudinal relaxation times are due to the so-called chemical shift anisotropy (csa) mechanism and reflect slight modifications of the toluene electronic distribution in the gel phase. NMR diffusion measurements by the pulse gradient spin-echo (PGSE) method allow us to determine the diffusion coefficient of toluene inside the organogel. It is roughly two-thirds of the one in pure toluene, thus indicating that self-diffusion is the only dynamical parameter to be slightly affected when the solvent is inside the gel structure. The whole set of experimental observations leads to the conclusion that, once the gel is formed, the solvent becomes essentially passive, although an important fraction is located within the gel structure.

  5. Understanding CO2 capture mechanisms in aqueous hydrazine via combined NMR and first-principles studies.

    Science.gov (United States)

    Lee, Byeongno; Stowe, Haley M; Lee, Kyu Hyung; Hur, Nam Hwi; Hwang, Son-Jong; Paek, Eunsu; Hwang, Gyeong S

    2017-09-13

    Aqueous amines are currently the most promising solution for large-scale CO2 capture from industrial sources. However, molecular design and optimization of amine-based solvents have proceeded slowly due to a lack of understanding of the underlying reaction mechanisms. Unique and unexpected reaction mechanisms involved in CO2 absorption into aqueous hydrazine are identified using (1)H, (13)C, and (15)N NMR spectroscopy combined with first-principles quantum-mechanical simulations. We find production of both hydrazine mono-carbamate (NH2-NH-COO(-)) and hydrazine di-carbamate ((-)OOC-NH-NH-COO(-)), with the latter becoming more populated with increasing CO2 loading. Exchange NMR spectroscopy also demonstrates that the reaction products are in dynamic equilibrium under ambient conditions due to CO2 exchange between mono-carbamate and di-carbamate as well as fast proton transfer between un-protonated free hydrazine and mono-carbamate. The exchange rate rises steeply at high CO2 loadings, enhancing CO2 release, which appears to be a unique property of hydrazine in aqueous solution. The underlying mechanisms of these processes are further evaluated using quantum mechanical calculations. We also analyze and discuss reversible precipitation of carbamate and conversion of bicarbonate to carbamates. The comprehensive mechanistic study provides useful guidance for optimal design of amine-based solvents and processes to reduce the cost of carbon capture. Moreover, this work demonstrates the value of a combined experimental and computational approach for exploring the complex reaction dynamics of CO2 in aqueous amines.

  6. Intracellular PHB conversion in a type II methanotroph studied by 13 C NMR

    NARCIS (Netherlands)

    Vecherskaya, M.; Dijkema, C.; Stams, A.J.M.

    2001-01-01

    Poly-g-hydroxybutyrate (PHB) formation under aerobic conditions via incorporation of [13C-2]acetate as a cosubstrate and its intracellular degradation under anaerobic conditions in a Type II methanotroph was studied by 13C NMR. During PHB synthesis in the presence of labelled acetate, low levels of

  7. MODERN NMR TECHNIQUES FOR THE STUDY OF LARGE PROTEINS IN SOLUTION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A number of important methodological developments in high resolution NMR spectroscopy have led to significant increases in the size limitations that previously impeded solution structural studies of macromolecules. Specifically, isotope labeling and TROSY triple resonance spectroscopy has resulted in substantial sensitivity and resolution gain for applications to large molecular weight proteins.

  8. Moisture in untreated, a cetylated, and furfurylated Norway spruce studied during drying using time domain NMR

    Science.gov (United States)

    Lisabeth G. Thygesen; Thomas Elder

    2008-01-01

    Using time domain NMR, the moisture in Norway spruce (Picea abies (L.) Karst.) sapwood subjected to four different treatments (never-dried, dried and remoistened, acetylated, and furfurylated) was studied during drying at 40°C, at sample average moisture contents above fiber saturation. Spin-spin relaxation time distributions were derived from CPMG...

  9. Complexation of roxatidine acetate hydrochloride with beta-cyclodextrin: NMR spectroscopic study.

    Science.gov (United States)

    Ali, S M; Maheshwari, A; Asmat, F

    2004-08-01

    A NMR spectroscopic study of mixtures of varying ratios of roxatidine acetate hydrochloride (RAH) and beta-cyclodextrin (beta-CD) in D2O revealed the formation of a 1:1 inclusion compound. The aromatic ring of RAH selectively penetrates the beta-CD cavity in preference to the piperidine ring.

  10. Solid-state NMR and ESR studies of activated carbons produced from pecan shells

    Science.gov (United States)

    Activated carbon from pecan shells has shown promise as an adsorbent in water treatment and sugar refining. However, the chemistry of the material is complex and not fully understood. We report here the application of solid state NMR and ESR to study the chemical structure, mobility, and pore volu...

  11. Synthesis, NMR data and theoretical study of semi-synthetic derivatives from trans-dehydrocrotonin

    Science.gov (United States)

    Soares, Breno Almeida; Medeiros Maciel, Maria Aparecida; Castro, Rosane Nora; Kaiser, Carlos R.; Firme, Caio Lima

    2016-03-01

    In this work, the 19-nor-diterpenoid clerodane-type dehydrocrotonin (t-DCTN) was a primary source for a two-step synthetic procedure. The catalytic hydrogenation of t-DCTN afforded the semi-synthetic trans-crotonin (t-CTN) in a highly stereospecific reaction confirmed by DFT calculations. The unsaturated carbonyl group of t-DCTN was reduced by NaBH4/EtOH providing an epimeric α-OH and β-OH mixture named t-CTN-OL. Both epimeric compound structures t-CTN-α-OL and t-CTN-β-OL were elucidated by 1D and 2D NMR spectral data. Comparison of NMR data from natural source of t-CTN was done to confirm the stereochemical authenticity of semi-synthetic t-CTN. Calculated NMR data for all described derivatives (semi-synthetic t-CTN and its t-CTN-OL epimeric mixture) were performed using B3LYP/6-311G++(d,p) level of theory which validated our previously developed NMR theoretical protocol for structural analyses of organic molecules. Topological data using Quantum Theory of Atoms in Molecules (QTAIM) of t-CTN quantified and qualified intramolecular interactions of its most stable conformer.

  12. An in-cell NMR study of monitoring stress-induced increase of cytosolic Ca{sup 2+} concentration in HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, Dambarudhar Shiba Sankar; Haremaki, Takahiro; Hamatsu, Jumpei; Inoue, Jin; Kamoshida, Hajime; Ikeya, Teppei; Mishima, Masaki [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan); Mikawa, Tsutomu [Cellular and Molecular Biology Unit, RIKEN Advanced Science Institute, Wako-shi, Saitama 351-0198 (Japan); Hayashi, Nobuhiro [Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 B-1, Nagatsuda-chou, Midori-ku, Yokohama, Kanagawa 226-8501 (Japan); Shirakawa, Masahiro [Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Ito, Yutaka, E-mail: ito-yutaka@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo 192-0373 (Japan)

    2013-09-06

    Highlights: •We performed time-resolved NMR observations of calbindin D{sub 9k} in HeLa cells. •Stress-induced increase of cytosolic Ca{sup 2+} concentration was observed by in-cell NMR. •Calbindin D{sub 9k} showed the state-transition from Mg{sup 2+}- to Ca{sup 2+}-bound state in cells. •We provide a useful tool for in situ monitoring of the healthiness of the cells. -- Abstract: Recent developments in in-cell NMR techniques have allowed us to study proteins in detail inside living eukaryotic cells. The lifetime of in-cell NMR samples is however much shorter than that in culture media, presumably because of various stresses as well as the nutrient depletion in the anaerobic environment within the NMR tube. It is well known that Ca{sup 2+}-bursts occur in HeLa cells under various stresses, hence the cytosolic Ca{sup 2+} concentration can be regarded as a good indicator of the healthiness of cells in NMR tubes. In this study, aiming at monitoring the states of proteins resulting from the change of cytosolic Ca{sup 2+} concentration during experiments, human calbindin D{sub 9k} (P47M + C80) was used as the model protein and cultured HeLa cells as host cells. Time-resolved measurements of 2D {sup 1}H–{sup 15}N SOFAST–HMQC experiments of calbindin D{sub 9k} (P47M + C80) in HeLa cells showed time-dependent changes in the cross-peak patterns in the spectra. Comparison with in vitro assignments revealed that calbindin D{sub 9k} (P47M + C80) is initially in the Mg{sup 2+}-bound state, and then gradually converted to the Ca{sup 2+}-bound state. This conversion process initiates after NMR sample preparation. These results showed, for the first time, that cells inside the NMR tube were stressed, presumably because of cell precipitation, the lack of oxygen and nutrients, etc., thereby releasing Ca{sup 2+} into cytosol during the measurements. The results demonstrated that in-cell NMR can monitor the state transitions of stimulated cells through the observation of

  13. NMR Study of HD Adsorbed in a Z-type Metal-Organic Framework

    Science.gov (United States)

    Ji, Yu; Tang, Y.; Hamida, J. A.; Sullivan, N. S.

    2012-12-01

    We report the results of measurements of the nuclear spin-lattice and spin-spin relaxation rates of hydrogen deuteride trapped in the mesoporous cages of a metal organic framework (MOF) for temperatures 2.2 hydrogen storage because of the high density of adsorption. NMR studies can provide important information about the molecular interactions and dynamics inside the cages of the MOF structure. Samples were studied with filling factors of 0.1 and 1.0 molecules per cage as determined by the adsorption isotherm at 77 K The results show strong peaks in the relaxation times at several well defined temperatures that are very different from the adsorption energy levels. The origin of these peaks is discussed in terms of the quantization of the translational degrees of freedom of the molecules inside the cages and the associated discrete energy levels. Measurements of the nuclear spin-spin relaxation times also provide an important measure of the diffusivity of hydrogen through the MOF structure which is a critical parameter for the use of MOFs for storage and transport.

  14. NMR characterization of hydrocarbon adsorption on calcite surfaces: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Bevilaqua, Rochele C. A.; Miranda, Caetano R. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Rigo, Vagner A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Universidade Tecnológica Federal do Paraná, UTFPR, Cornélio Procópio, PR (Brazil); Veríssimo-Alves, Marcos [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, UFABC, Santo André, SP (Brazil); Departamento de Física, ICEx, Universidade Federal Fluminense, UFF, Volta Redonda, RJ (Brazil)

    2014-11-28

    The electronic and coordination environment of minerals surfaces, as calcite, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca{sup 2+}. Since calcite is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on calcite surface (CaCO{sub 3} (101{sup ¯}4)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for {sup 43}Ca, {sup 13}C, and {sup 17}O in calcite surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for calcite, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the calcite surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.

  15. Water exchange in plant tissue studied by proton NMR in the presence of paramagnetic centers.

    Science.gov (United States)

    Bacić, G; Ratković, S

    1984-04-01

    The proton NMR relaxation of water in maize roots in the presence of paramagnetic centers, Mn2+, Mn- EDTA2 -, and dextran-magnetite was measured. It was shown that the NMR method of Conlon and Outhred (1972, Biochem. Biophys. Acta. 288:354-361) can be applied to a heterogenous multicellular system, and the water exchange time between cortical cells and the extracellular space can be calculated. The water exchange is presumably controlled by the intracellular unstirred layers. The Mn- EDTA2 - complex is a suitable paramagnetic compound for complex tissue, while the application of dextran-magnetite is probably restricted to studies of water exchange in cell suspensions. The water free space of the root and viscosity of the cells cytoplasm was estimated with the use of Mn- EDTA2 -. The convenience of proton NMR for studying the multiphase uptake of paramagnetic ions by plant root as well as their transport to leaves is demonstrated. A simple and rapid NMR technique (spin-echo recovery) for continuous measurement of the uptake process is presented.

  16. Homonuclear 1H NMR and circular dichroism study of the HIV-1 Tat Eli variant

    Science.gov (United States)

    Watkins, Jennifer D; Campbell, Grant R; Halimi, Hubert; Loret, Erwann P

    2008-01-01

    Background The HIV-1 Tat protein is a promising target to develop AIDS therapies, particularly vaccines, due to its extracellular role that protects HIV-1-infected cells from the immune system. Tat exists in two different lengths, 86 or 87 residues and 99 or 101 residues, with the long form being predominant in clinical isolates. We report here a structural study of the 99 residue Tat Eli variant using 2D liquid-state NMR, molecular modeling and circular dichroism. Results Tat Eli was obtained from solid-phase peptide synthesis and the purified protein was proven biologically active in a trans-activation assay. Circular dichroism spectra at different temperatures up to 70°C showed that Tat Eli is not a random coil at 20°C. Homonuclear 1H NMR spectra allowed us to identify 1639 NMR distance constraints out of which 264 were interresidual. Molecular modeling satisfying at least 1474 NMR constraints revealed the same folding for different model structures. The Tat Eli model has a core region composed of a part of the N-terminus including the highly conserved Trp 11. The extra residues in the Tat Eli C-terminus protrude from a groove between the basic region and the cysteine-rich region and are well exposed to the solvent. Conclusion We show that active Tat variants share a similar folding pattern whatever their size, but mutations induce local structural changes. PMID:18808674

  17. Using NMR to study small molecule adsorption in metal organic frameworks

    Science.gov (United States)

    Lopez, M. G.; Canepa, P.; Thonhauser, T.

    2013-03-01

    We calculate the carbon nuclear magnetic resonance (NMR) chemical shift for the CO2 molecule and the hydrogen shift for both H2 and H2O inside the metal organic framework structure Mg-MOF74 using ab initio calculations at the density functional theory level[1,2] with the van der Waals density functional (vdW-DF).[3] These shifts are obtained while placing the small molecules throughout the structure, including the calculated adsorption site for various loading scenarios. Our binding energy results agree well with previous experiments and calculation, and the NMR calculations show that it is reasonable to expect an experimentally observable change in the chemical shift depending on adsorbant, position, and loading. By providing this mapping of chemical shift to position and loading for these adsorbants, we argue that NMR probes could be used to provide information about the position at which these small molecules bind within the MOF and provide information about the loading of the adsorbed molecule.

  18. NMR and molecular dynamics studies of the interaction of melatonin with calmodulin

    Science.gov (United States)

    Turjanski, Adrián G.; Estrin, Darío A.; Rosenstein, Ruth E.; McCormick, John E.; Martin, Stephen R.; Pastore, Annalisa; Biekofsky, Rodolfo R.; Martorana, Vincenzo

    2004-01-01

    Pineal hormone melatonin (N-acetyl-5-methoxytryptamine) is thought to modulate the calcium/calmodulin signaling pathway either by changing intracellular Ca2+ concentration via activation of its G-protein–coupled membrane receptors, or through a direct interaction with calmodulin (CaM). The present work studies the direct interaction of melatonin with intact calcium-saturated CaM both experimentally, by fluorescence and nuclear magnetic resonance spectroscopies, and theoretically, by molecular dynamics simulations. The analysis of the experimental data shows that the interaction is calcium-dependent. The affinity, as obtained from monitoring 15N and 1H chemical shift changes for a melatonin titration, is weak (in the millimolar range) and comparable for the N- and C-terminal domains. Partial replacement of diamagnetic Ca2+ by paramagnetic Tb3+ allowed the measurement of interdomain NMR pseudocontact shifts and residual dipolar couplings, indicating that each domain movement in the complex is not correlated with the other one. Molecular dynamics simulations allow us to follow the dynamics of melatonin in the binding pocket of CaM. Overall, this study provides an example of how a combination of experimental and theoretical approaches can shed light on a weakly interacting system of biological and pharmacological significance. PMID:15498938

  19. Structure and Dynamics in Amphiphilic Bilayers: NMR and MD simulation Studies

    OpenAIRE

    2013-01-01

    Solid-state nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations were employed to study molecular structure and dynamics in amphiphilic bilayers. This thesis reports on method development and practical applications to two types of bilayer systems: simple cell membrane models composed of phosphatidylcholine lipids and cholesterol; and liquid crystals composed of ethyleneoxide-based surfactants often used in technological applications and in fundamental studies ...

  20. Enzymatic synthesis and NMR studies of acylated sucrose acetates

    NARCIS (Netherlands)

    Steverink-De Zoete, M.C.; Kneepkens, M.F.M.; Waard, de P.; Woudenberg-van Oosterom, M.; Gotlieb, K.F.; Slaghek, T.

    1999-01-01

    The lipase-catalyzed esterification of partially acetylated sucrose has been studied. It was shown that the chemical acetylation increased the reaction rate of the subsequent enzymatic acylation. Thus it was possible to perform the enzymatic acylation in the absence of solvents while underivatized s

  1. NMR Study of Damage on Isolated Perfused Rat Heart Exposed to Ischemia and Hypoxia

    Institute of Scientific and Technical Information of China (English)

    罗雪春; 闫永彬; 张日清; 王小寅; 范礼理

    2001-01-01

    Myocardial ischemia is the most common and primary cause of myocardium damage. Numerous conventional techniques and methods have been developed for ischemia and reperfusion studies. However, because of damage to the heart sample, most of these techniques can not be used to continuously monitor the full dynamic course of the myocardial metabolic pathway. The nuclear magnetic resonnance (NMR) surface coil technique, which overcomes the limitations of conventional instrumentation, can be used to quantitatively study every stage of the perfused heart (especially after perfusion stoppage) continuously, dynamically, and without damage under normal or designed physiological conditions at the molecular level. In this paper, 31p-NMR was used to study the effects of ischemia and hypoxia on isolated perfused hearts. The results show that complete hypoxia caused more severe functional damage to the myocardial cells than complete ischemia.

  2. 14N NMR Spectroscopy Study of Binding Interaction between Sodium Azide and Hydrated Fullerene

    Directory of Open Access Journals (Sweden)

    Tamar Chachibaia

    2017-04-01

    Full Text Available Our study is the first attempt to study the interaction between NaN3 and hydrated fullerenes C60 by means of a non-chemical reaction-based approach. The aim is to study deviations of signals obtained by 14N NMR spectroscopy to detect the binding interaction between sodium azide and hydrated fullerene. We considered 14N NMR spectroscopy as one of the most suitable methods for the characterization of azides to show resonance signals corresponding to the three non-equivalent nitrogen atoms. The results demonstrate that there are changes in the chemical shift positions and line-broadening, which are related to the different molar ratios of NaN3:C60 in the samples.

  3. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  4. EPR and NMR studies of amorphous aluminum borates

    NARCIS (Netherlands)

    Simon, S.; Pol, A. van der; Reijerse, E.J.; Kentgens, A.P.M.; Moorsel, G.J.M.P. van; Boer, E. de

    1994-01-01

    Amorphous aluminium borates, Al2(1–x)B2xO3 with O [less-than-or-eq]x[less-than-or-eq] 0.5, prepared from mixtures of aluminium nitrate, boric acid and glycerol, have been studied by EPR and 27Al MASNMR as a function of composition and heat-treatment temperature (Tt[less-than-or-eq] 860 °C). EPR stud

  5. Carbon-13 NMR spectroscopy of biological systems

    CERN Document Server

    Beckmann, Nicolau

    1995-01-01

    This book is intended to provide an in-depth understanding of 13C NMR as a tool in biological research. 13C NMR has provided unique information concerning complex biological systems, from proteins and nucleic acids to animals and humans. The subjects addressed include multidimensional heteronuclear techniques for structural studies of molecules in the liquid and solid states, the investigation of interactions in model membranes, the elucidation of metabolic pathwaysin vitro and in vivo on animals, and noninvasive metabolic studies performed on humans. The book is a unique mix of NMR methods and biological applications which makes it a convenient reference for those interested in research in this interdisciplinary area of physics, chemistry, biology, and medicine.Key Features* An interdisciplinary text with emphasis on both 13C NMR methodology and the relevant biological and biomedical issues* State-of-the-art 13C NMR techniques are described; Whenever possible, their advantages over other approaches are empha...

  6. Structure and dynamics of aqueous 2-propanol: a THz-TDS, NMR and neutron diffraction study.

    Science.gov (United States)

    McGregor, James; Li, Ruoyu; Zeitler, J Axel; D'Agostino, Carmine; Collins, James H P; Mantle, Mick D; Manyar, Haresh; Holbrey, John D; Falkowska, Marta; Youngs, Tristan G A; Hardacre, Christopher; Stitt, E Hugh; Gladden, Lynn F

    2015-11-11

    Aqueous liquid mixtures, in particular, those involving amphiphilic species, play an important role in many physical, chemical and biological processes. Of particular interest are alcohol/water mixtures; however, the structural dynamics of such systems are still not fully understood. Herein, a combination of terahertz time-domain spectroscopy (THz-TDS) and NMR relaxation time analysis has been applied to investigate 2-propanol/water mixtures across the entire composition range; while neutron diffraction studies have been carried out at two specific concentrations. Excellent agreement is seen between the techniques with a maximum in both the relative absorption coefficient and the activation energy to molecular motion occurring at ∼90 mol% H2O. Furthermore, this is the same value at which well-established excess thermodynamic functions exhibit a maximum/minimum. Additionally, both neutron diffraction and THz-TDS have been used to provide estimates of the size of the hydration shell around 2-propanol in solution. Both methods determine that between 4 and 5 H2O molecules per 2-propanol are found in the 2-propanol/water clusters at 90 mol% H2O. Based on the acquired data, a description of the structure of 2-propanol/water across the composition range is presented.

  7. NMR spectroscopy study of local correlations in water

    Science.gov (United States)

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Stanley, H. Eugene

    2016-12-01

    Using nuclear magnetic resonance we study the dynamics of the hydrogen bond (HB) sub-domains in bulk and emulsified water across a wide temperature range that includes the supercooled regime. We measure the proton spin-lattice T1 and spin-spin T2 relaxation times to understand the hydrophilic interactions that determine the properties of water. We use (i) the Bloembergen, Purcell, and Pound approach that focuses on a single characteristic correlation time τc, and (ii) the Powles and Hubbard approach that measures the proton rotational time τθ. We find that when the temperature is low both relaxation times are strongly correlated when the HB lifetime is long, and that when the temperature is high a decrease in the HB lifetime destroys the water clusters and decouples the dynamic modes of the system.

  8. Interaction of ferulic acid derivatives with human erythrocytes monitored by pulse field gradient NMR diffusion and NMR relaxation studies.

    Science.gov (United States)

    Anselmi, Cecilia; Bernardi, Francesca; Centini, Marisanna; Gaggelli, Elena; Gaggelli, Nicola; Valensin, Daniela; Valensin, Gianni

    2005-04-01

    Ferulic acid (Fer), a natural anti-oxidant and chemo-protector, is able to suppress experimental carcinogenesis in the forestomach, lungs, skin, tongue and colon. Several Fer derivatives have been suggested as promising candidates for cancer prevention, being the biological activity related also to the capacity of partitioning between aqueous and lipid phases. In the present work, pulsed field gradient (PFG) NMR diffusion measurement and NMR relaxation rates have been adopted for investigating the interaction of three Fer derivatives (Fer-C11, Fer-C12 and Fer-C13) with human erythrocytes. Binding to the erythrocyte membrane has been shown for all derivatives, which displayed a similar interaction mode such that the aromatic moiety and the terminal part of the alkyl chain were the most affected. Quantitative analysis of the diffusion coefficients was used to show that Fer-C12 and Fer-C13 display higher affinity for the cell membrane when compared with Fer-C11. These findings agree with the higher anti-oxidant activity of the two derivatives.

  9. Applications of solid-state Nuclear Magnetic Resonance (NMR) in studies of Portland cements-based materials

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Andersen, Morten Daugaard; Jakobsen, Hans Jørgen

    2007-01-01

    Solid-state NMR spectroscopy represents an important research tool in the characterization of a range of structural properties for cement-based materials. Different approaches of the technique can be used to obtain information on hydration kinetics, mobile and bound water, porosity, and local...... atomic structures. After a short introduction to these NMR techniques, it is exemplified how magic-angle spinning (MAS) NMR can provide quantitative and structural information about specific phases in anhydrous and hydrated Portland cements with main emphasis on the incorporation of Al3+ ions...

  10. Solid state 31NMR studies of the conversion of amorphous tricalcium phosphate to apatitic tricalcium phosphate.

    Science.gov (United States)

    Roberts, J E; Heughebaert, M; Heughebaert, J C; Bonar, L C; Glimcher, M J; Griffin, R G

    1991-12-01

    The hydrolytic conversion of a solid amorphous calcium phosphate of empirical formula Ca9 (PO4)6 to a poorly crystalline apatitic phase, under conditions where Ca2+ and PO4(3-) were conserved, was studied by means of solid-state magic-angle sample spinning 31P-NMR (nuclear magnetic resonance). Results showed a gradual decrease in hydrated amorphous calcium phosphate and the formation of two new PO4(3-)-containing components: an apatitic component similar to poorly crystalline hydroxyapatite and a protonated PO4(3-), probably HPO4(2-) in a dicalcium phosphate dihydrate (DCPD) brushite-like configuration. This latter component resembles the brushite-like HPO4(2-) component previously observed by 31P-NMR in apatitic calcium phosphates of biological origin. Results were consistent with previous studies by Heughebaert and Montel [18] of the kinetics of the conversion of amorphous calcium phosphate to hydroxyapatite under the same conditions.

  11. Conformational equilibrium of phenylacetic acid and its halogenated analogues through theoretical studies, NMR and IR spectroscopy

    Science.gov (United States)

    Levandowski, Mariana N.; Rozada, Thiago C.; Melo, Ulisses Z.; Basso, Ernani A.; Fiorin, Barbara C.

    2017-03-01

    This paper presents a study on the conformational preferences of phenylacetic acid (PA) and its halogenated analogues (FPA, CPA, BPA). To clarify the effects that rule these molecules' behaviour, theoretical calculations were used, for both the isolated phase and solution, combined with nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Most conformations of phenylacetic acid and its halogenated derivatives are stabilized through the hyperconjugative effect, which rules the conformational preference. NMR analyses showed that even with the variation in medium polarity, there was no significant change in the conformation population. Infrared spectroscopy showed similar results for all compounds under study. In most spectra, two bands were found through the carbonyl deconvolution, which is in accordance with the theoretical data. It was possible to prove that variation in the nature of the substituent in the ortho position had no significant influence on the conformational equilibrium.

  12. Theoretical and experimental IR, Raman and NMR spectra in studying the electronic structure of 2-nitrobenzoates

    Science.gov (United States)

    Świsłocka, R.; Samsonowicz, M.; Regulska, E.; Lewandowski, W.

    2007-05-01

    The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-nitrobenzoic acid (2-NBA) was studied. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6-311++G ∗∗ basis set. The theoretical IR and NMR spectra were obtained. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-nitrobenzoic acid salts of alkali metals were also recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 2-nitrobenzoates (2-NB) and ionic potential, electronegativity, atomic mass and affinity of metals were found. The chemical shifts of protons and carbons ( 1H, 13C NMR) in the series of studied alkali metal 2-nitrobenzoates were observed too. The calculated parameters were compared to experimental characteristic of studied compounds.

  13. The Surface of Nanoparticle Silicon as Studied by Solid-State NMR

    Directory of Open Access Journals (Sweden)

    Gary E. Maciel

    2012-12-01

    Full Text Available The surface structure and adjacent interior of commercially available silicon nanopowder (np-Si was studied using multinuclear, solid-state NMR spectroscopy. The results are consistent with an overall picture in which the bulk of the np-Si interior consists of highly ordered (“crystalline” silicon atoms, each bound tetrahedrally to four other silicon atoms. From a combination of 1H, 29Si and 2H magic-angle-spinning (MAS NMR results and quantum mechanical 29Si chemical shift calculations, silicon atoms on the surface of “as-received” np-Si were found to exist in a variety of chemical structures, with apparent populations in the order (a (Si–O–3Si–H > (b (Si–O–3SiOH > (c (HO–nSi(Sim(–OSi4−m−n ≈ (d (Si–O–2Si(HOH > (e (Si–O–2Si(–OH2 > (f (Si–O–4Si, where Si stands for a surface silicon atom and Si represents another silicon atom that is attached to Si by either a Si–Si bond or a Si–O–Si linkage. The relative populations of each of these structures can be modified by chemical treatment, including with O2 gas at elevated temperature. A deliberately oxidized sample displays an increased population of (Si–O–3Si–H, as well as (Si–O–3SiOH sites. Considerable heterogeneity of some surface structures was observed. A combination of 1H and 2H MAS experiments provide evidence for a substantial population of silanol (Si–OH moieties, some of which are not readily H-exchangeable, along with the dominant Si–H sites, on the surface of “as-received” np-Si; the silanol moieties are enhanced by deliberate oxidation. An extension of the DEPTH background suppression method is also demonstrated that permits measurement of the T2 relaxation parameter simultaneously with background suppression.

  14. Multinuclear NMR and crystallographic studies of triorganotin valproates and their in vitro antifungal activities

    Science.gov (United States)

    de Morais, Bárbara P.; de Lima, Geraldo M.; Pinheiro, Carlos B.; San Gil, Rosane A. S.; Takahashi, Jacqueline A.; Menezes, Daniele C.; Ardisson, José D.

    2015-08-01

    The reactions of triorganotin chlorides and sodium valproate, Na(OVp), yielded three triorganotin valproates [{SnMe3(OVp)}n] (1), [{SnBu3(OVp)}n] (2) and [SnPh3(OVp)] (3). All complexes have been authenticated in terms of infrared, 1H and 13C NMR, and solution- and solid-state 119Sn NMR, 119Sn Mössbauer and X-ray crystallography. The 119Sn NMR experiments provided important informations concerning the structures of (1)-(3) in solution and in the solid state. The X-ray experiments revealed the double-polymeric chain of complex (1), in which the geometry at the Sn(IV) is trigonal bipyramidal with intermolecular valproate bridges. The structure of complex (3) was re-determined and the new data show the tin cation at the centre of a distorted trigonal bipyramid, and not coordinated by four electron donating groups. The biological activity of all derivatives has been screened in terms of IC50 (μmol L-1) against C. albicans (ATCC 18804), C. tropicalis (ATCC 750), C. glabrata (ATCC 90030), C. parapsilosis (ATCC 22019), C. lusitaniae (CBS 6936) and C. dubliniensis (clinical isolate 28). Complex (3) exhibited the best biocide activity.

  15. IN SITU MAGIC ANGLE SPINNING NMR FOR STUDYING GEOLOGICAL CO(2) SEQUESTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, David W.; Turcu, Romulus VF; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Kwak, Ja Hun; Felmy, Andrew R.; Hu, Jian Z.

    2011-03-27

    Geological carbon sequestration (GCS) is one of the most promising ways of mitigating atmospheric greenhouse gases (1-3). Mineral carbonation reactions are potentially important to the long-term sealing effectiveness of caprock but remain poorly predictable, particularly in low-water supercritical CO2 (scCO2)-dominated environments where the chemistry has not been adequately explored. In situ probes that provide molecular-level information is desirable for investigating mechanisms and rates of GCS mineral carbonation reactions. MAS-NMR is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, or a supercritical state, or a mixture thereof (4,5). However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS rotor (6,7), where non-metal materials must be used. In this work, we report development of a unique high pressure MAS NMR capability, and its application to mineral carbonation chemistry in scCO2 under geologically relevant temperatures and pressures.

  16. NMR study of Corynebacterium melassecola metabolism; Etude du metabolisme de corynebacterium melassecola par RMN

    Energy Technology Data Exchange (ETDEWEB)

    Rollin, C.; Morgant, V.; Guyonvarch, A. [Centre ORSAN, 91 - Les Ulis (France); Guerquin Kern, J.L. [Institut Curie, 91 - Orsay (France)

    1994-12-31

    Corynebacterium melassecola is a microorganism producing glutamic acid, an aminate acid used as food additive. Knowledge of its metabolism is essential for improving the phyla. A study is carried out on intracellular extracts with NMR spectrometry in order to determine certain glucose catabolism pathways using a partial isotopic enrichment with (1-{sup 13}C) or (6-{sup 13}C) glucose. Results demonstrate the particular metabolism of Corynebacteria. 2 tabs., 3 refs.

  17. NMR and EPR Studies of Free-Radical Intermediates from Experiments Mimicking the Winds on Mars

    DEFF Research Database (Denmark)

    Jakobsen, Hans J.; Song, Likai; Gan, Zhehong

    2016-01-01

    A new kind of solid gas chemical reactions has been investigated using solid-state powder H-2, C-13, and Si-29 NMR and EPR spectroscopies. These studies involve reactions between a silicate-created Si free-radical intermediate and a few ordinary gases such as isotopically H-2-, C-13-, and O-17......)-C-13, (encapsulation of the gas) and the indication of a congested methyl group in the product from reaction with methane....

  18. Exfoliation Dynamics of Laponite Clay in Aqueous Suspensions Studied by NMR Relaxometry

    OpenAIRE

    2016-01-01

    The interaction between Laponite and other constituents in complex systems greatly depends on its available surface area. We report a study of exfoliation dynamics of Laponite in aqueous suspensions by NMR relaxometry. It showed that Laponite particles exfoliate to the same extent in a concentration range of 0.5-3% w/w. Faster increase of specific wetted surface area of Laponite particles in more concentrated suspensions suggests faster exfoliation of disc-shaped Laponite platelets from the i...

  19. Study of an S = 1 Ni(II) pincer electrocatalyst precursor for aqueous hydrogen production based on paramagnetic 1H NMR.

    Science.gov (United States)

    Luca, Oana R; Konezny, Steven J; Paulson, Eric K; Habib, Fatemah; Luthy, Kurt M; Murugesu, Muralee; Crabtree, Robert H; Batista, Victor S

    2013-06-28

    A tridentate NNN Ni(II) complex, shown to be an electrocatalyst for aqueous H2 production at low overpotentials, is studied by using temperature-dependent paramagnetic (1)H NMR. The NMR T1 relaxation rates, temperature dependence of the chemical shifts, and dc SQUID magnetic susceptibility are correlated to DFT chemical shifts and compared with the properties of a diamagnetic Zn analogue complex. The resulting characterization provides an unambiguous assignment of the six proton environments in the meridionally coordinating tridentate NNN ligand. The demonstrated NMR/DFT methodology should be valuable in the search for appropriate ligands to optimize the reactivity of 3d metal complexes bound to attract increasing attention in catalytic applications.

  20. NMR study of a membrane protein in detergent-free aqueous solution.

    Science.gov (United States)

    Zoonens, Manuela; Catoire, Laurent J; Giusti, Fabrice; Popot, Jean-Luc

    2005-06-21

    One of the major obstacles to membrane protein (MP) structural studies is the destabilizing effect of detergents. Amphipols (APols) are short amphipathic polymers that can substitute for detergents to keep MPs water-soluble under mild conditions. In the present work, we have explored the feasibility of studying the structure of APol-complexed MPs by NMR. As a test MP, we chose the 171-residue transmembrane domain of outer MP A from Escherichia coli (tOmpA), whose x-ray and NMR structures in detergent are known. 2H,15N-labeled tOmpA was produced as inclusion bodies, refolded in detergent solution, trapped with APol A8-35, and the detergent removed by adsorption onto polystyrene beads. The resolution of transverse relaxation-optimized spectroscopy-heteronuclear single-quantum correlation spectra of tOmpA/A8-35 complexes was found to be close to that of the best spectra obtained in detergent solutions. The dispersion of chemical shifts indicated that the protein had regained its native fold and retained it during the exchange of surfactants. MP-APol interactions were mapped by substituting hydrogenated for deuterated A8-35. The resulting dipolar broadening of amide proton linewidths was found to be limited to the beta-barrel region of tOmpA, indicating that A8-35 binds specifically to the hydrophobic transmembrane surface of the protein. The potential of this approach to MP studies by solution NMR is discussed.

  1. Bacterial expression and isotope labeling of AIMP1/p43 codosome protein for structural studies by multidimensional NMR spectroscopy

    Directory of Open Access Journals (Sweden)

    Vorobyova N. V.

    2015-04-01

    Full Text Available AIMP1/p43 protein is a structural component of multisynthetase complex (codosome in eukaryotes, which reveals both tRNA binding and cytokine activities. Aim. Bacterial expression and purification of isotopically-labeled recombinant AIMP1/p43 protein in E. coli cells for studying its solution structure by multidimensional NMR spectroscopy. Methods. AIMP1/p43 protein was expressed in E. coli BL21(DE3pLysE cells on M9 minimal medium with 15N isotope labeling and purified by metal-chelated chromatography. Heteronuclear 2D 1H-15N NMR experiments were performed in solution at 293 K on Agilent DDR2 800 NMR spectrometer. Results. The AIMP1/p43 protein was obtained in uniformly 15N-labeled form as an NMR sample. A high dispersion of resonance signals in the 2D 1H-15N HSQC NMR spectra confirmed the presence of its compact 3D protein structure. The NMR spectrum of AIMP1/p43 demonstrated a high signal-to-noise ratio and sufficient stability to acquire other multidimensional NMR data sets for determination of the structure of AIMP1/p43 protein in solution. Conclusions. The 15N-labeled AIMP1/p43 protein was stable for 4–7 days, which makes possible acquiring the critical NMR experimental data for detailed structural analysis in solution. Our data on the initial NMR spectra indicated the presence of some additional signals in comparison with the NMR spectrum of EMAP II which could be assigned to amino acids of the N-terminal α-helical fragment of AIMP1/p43.

  2. A high-resolution solid-state NMR approach for the structural studies of bicelles.

    Science.gov (United States)

    Dvinskikh, Sergey; Dürr, Ulrich; Yamamoto, Kazutoshi; Ramamoorthy, Ayyalusamy

    2006-05-17

    Bicelles are increasingly being used as membrane mimicking systems in NMR experiments to investigate the structure of membrane proteins. In this study, we demonstrate the effectiveness of a 2D solid-state NMR approach that can be used to measure the structural constraints, such as heteronuclear dipolar couplings between 1H, 13C, and 31P nuclei, in bicelles without the need for isotopic enrichment. This method does not require a high radio frequency power unlike the presently used rotating-frame separated-local-field (SLF) techniques, such as PISEMA. In addition, multiple dipolar couplings can be measured accurately, and the presence of a strong dipolar coupling does not suppress the weak couplings. High-resolution spectra obtained from magnetically aligned DMPC:DHPC bicelles even in the presence of peptides suggest that this approach will be useful in understanding lipid-protein interactions that play a vital role in shaping up the function of membrane proteins.

  3. Decomposition of adsorbed VX on activated carbons studied by 31P MAS NMR.

    Science.gov (United States)

    Columbus, Ishay; Waysbort, Daniel; Shmueli, Liora; Nir, Ido; Kaplan, Doron

    2006-06-15

    The fate of the persistent OP nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) {(DES)2}. Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed.

  4. /sup 13/C NMR studies of the molecular flexibility of antidepressants

    Energy Technology Data Exchange (ETDEWEB)

    Munro, S.L.; Andrews, P.R.; Craik, D.J.; Gale, D.J.

    1986-02-01

    The solution dynamics of a series of clinically potent antidepressants have been investigated by measuring /sup 13/C NMR relaxation parameters. Correlation times and internal motional rates were calculated from spin-lattice relaxation times and nuclear Overhauser effects for the protonated carbons in mianserin, imipramine-like antidepressants, and amitriptyline-like antidepressants. These data were interpreted in terms of overall molecular tumbling, internal rotations, and inherent flexibility of these structures. Of particular interest was the conformational variability of the tricyclic nucleus of the tricyclic antidepressants, where the data indicated a fivefold difference in mobility of the dimethylene bridge of imipramine-like antidepressants relative to amitriptyline-like compounds. The implications of such a difference in internal motions is discussed in relation to previous NMR studies and to the reported differences in pharmacological activity of these antidepressants.

  5. Theoretical DFT and experimental NMR studies on uracil and 5-fluorouracil

    Science.gov (United States)

    Blicharska, Barbara; Kupka, Teobald

    2002-08-01

    The results of extended MO calculations using density functional theory (DFT) approximation and multinuclear HR NMR studies on uracil (U) and 5-fluorouracil (5FU) are reported. The performance of the B3PW91 hybrid density functional was compared with the ab initio restricted Hartree-Fock (RHF) method. With the basis set 6-31G ∗, or better quality, the DFT calculated bond lengths, dipole moments and harmonic stretching vibrations were predicted in good agreement with available experimental data. Structure and harmonic vibrations of U and 5FU were also calculated in the presence of water within a simple Onsager model. A linear correlation between proton and carbon GIAO NMR shieldings of uracil and 5FU and experimental data was shown.

  6. Structure-activity study of thiazides by magnetic resonance methods (NQR, NMR, EPR) and DFT calculations.

    Science.gov (United States)

    Latosińska, J N

    2005-01-01

    The paper presents a comprehensive analysis of the relationship between the electronic structure of thiazides and their biological activity. The compounds of interest were studied in solid state by the resonance methods nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) and quantum chemistry (ab inito and DFT) methods. Detailed parallel analysis of the spectroscopic parameters such as quadrupole coupling constant (QCC) NQR chemical shift (delta), chemical shift anisotropy (CSA), asymmetry parameter (eta), NMR and hyperfine coupling constant (A), EPR was performed and the electronic effects (polarisation and delocalisation) were revealed and compared. Biological activity of thiazides has been found to depend on many factors, but mainly on the physico-chemical properties whose assessment was possible on the basis of electron density determination in the molecules performed by experimental and theoretical methods.

  7. A High Resolution Solid State NMR Approach for the Structural Studies of Bicelles

    Science.gov (United States)

    Dvinskikh, Sergey; Dürr, Ulrich; Yamamoto, Kazutoshi; Ramamoorthy, Ayyalusamy

    2008-01-01

    Bicelles are increasingly being used as membrane mimicking systems in NMR experiments to investigate the structure of membrane proteins. In this study, we demonstrate the effectiveness of a 2D solid-state NMR approach that can be used to measure the structural constraints such as heteronuclear dipolar couplings between 1H, 13C and 31P nuclei in bicelles without the need for isotopic enrichment. This method does not require a high radio frequency power unlike the presently used rotating-frame separated-local-field (SLF) techniques like PISEMA. In addition, multiple dipolar couplings can be measured accurately and the presence of a strong dipolar coupling does not suppress the weak couplings. High resolution spectra obtained from magnetically aligned DMPC:DHPC bicelles even in the presence of peptides suggest that this approach will be useful in understanding lipid-protein interactions that play a vital role in shaping up the function of membrane proteins. PMID:16683791

  8. Decomposition of adsorbed VX on activated carbons studied by {sup 31}P MAS NMR

    Energy Technology Data Exchange (ETDEWEB)

    Ishay Columbus; Daniel Waysbort; Liora Shmueli; Ido Nir; Doron Kaplan [Israel Institute for Biological Research, Ness Ziona (Israel). Departments of Organic Chemistry and Physical Chemistry

    2006-06-15

    The fate of the persistent OP nerve agent O-ethyl S-(2-(diisopropylamino)ethyl) methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. Four types of activated carbon were used, including coal-based BPL. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) ((DES){sub 2}). Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed. 17 refs., 6 figs., 3 tabs.

  9. Chiral Magnetism in an Itinerant Helical Magnet, MnSi - An Extended 29Si NMR Study

    Science.gov (United States)

    Yasuoka, Hiroshi; Motoya, Kiyoichiro; Majumder, Mayukh; Witt, Sebastian; Krellner, Cornelius; Baenitz, Michael

    2016-07-01

    The microscopic magnetism in the helical, conical and ferromagnetically polarized phases in an itinerant helical magnet, MnSi, has been studied by an extended 29Si NMR at zero field and under external magnetic fields. The temperature dependence of the staggered moment, MQ(T), determined by the 29Si NMR frequency, ν(T), and the nuclear relaxation rate, 1/T1(T), at zero field is in general accord with the SCR theory for weak itinerant ferromagnetic metals and its extension to helical magnets. The external field dependence of resonance frequency, ν(H), follows a vector sum of the contributions from the atomic hyperfine and macroscopic fields with a field induced moment characteristic to itinerant magnets. A discontinuous jump of the resonance frequency at the critical field, Hc, between the conical and the polarized phases has also been found, which suggests a first order like change of the electronic states at Hc.

  10. Mobility of TOAC spin-labelled peptides binding to the Src SH3 domain studied by paramagnetic NMR

    Energy Technology Data Exchange (ETDEWEB)

    Lindfors, Hanna E. [Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories (Netherlands); Koning, Peter E. de; Wouter Drijfhout, Jan [Leiden University Medical Centre, Department of Immunohematology and Blood Transfusion (Netherlands); Venezia, Brigida; Ubbink, Marcellus [Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories (Netherlands)], E-mail: m.ubbink@chem.leidenuniv.nl

    2008-07-15

    Paramagnetic relaxation enhancement provides a tool for studying the dynamics as well as the structure of macromolecular complexes. The application of side-chain coupled spin-labels is limited by the mobility of the free radical. The cyclic, rigid amino acid spin-label TOAC (2,2,6,6-Tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid), which can be incorporated straightforwardly by peptide synthesis, provides an attractive alternative. In this study, TOAC was incorporated into a peptide derived from focal adhesion kinase (FAK), and the interaction of the peptide with the Src homology 3 (SH3) domain of Src kinase was studied, using paramagnetic NMR. Placing TOAC within the binding motif of the peptide has a considerable effect on the peptide-protein binding, lowering the affinity substantially. When the TOAC is positioned just outside the binding motif, the binding constant remains nearly unaffected. Although the SH3 domain binds weakly and transiently to proline-rich peptides from FAK, the interaction is not very dynamic and the relative position of the spin-label to the protein is well-defined. It is concluded that TOAC can be used to generate reliable paramagnetic NMR restraints.

  11. 39K, 23Na, and 31P NMR Studies of Ion Transport in Saccharomyces cerevisiae

    Science.gov (United States)

    Ogino, T.; den Hollander, J. A.; Shulman, R. G.

    1983-09-01

    The relationship between efflux and influx of K+, Na+, and intracellular pH (pHin) in yeast cells upon energizing by oxygenation was studied by using the noninvasive technique of 39K, 23Na, and 31P NMR spectroscopy. By introducing an anionic paramagnetic shift reagent, Dy3+(P3O105-)2, into the medium, NMR signals of intra- and extracellular K+ and Na+ could be resolved, enabling us to study ion transport processes by NMR. Measurements showed that 40% of the intracellular K+ and Na+ in yeast cells contributed to the NMR intensities. By applying this correction factor, the intracellular ion concentrations were determined to be 130-170 mM K+ and 2.5 mM Na+ for fresh yeast cells. With the aid of a home-built solenoidal coil probe for 39K and a double-tuned probe for 23Na and 31P, we could follow time courses of K+ and Na+ transport and of pHin with a time resolution of 1 min. It was shown that H+ extrusion is correlated with K+ uptake and not with Na+ uptake upon energizing yeast cells by oxygenation. When the cells were deenergized after the aerobic period, K+ efflux, H+ influx, and Na+ influx were calculated to be 1.6, 1.5, and 0.15 μ mol/min per ml of cell water, respectively. Therefore, under the present conditions, K+ efflux is balanced by exchange for H+ with an approximate stoichiometry of 1:1.

  12. GLUCOSE AND LACTATE METABOLISM IN THE AWAKE AND STIMULATED RAT: A 13C-NMR STUDY.

    Directory of Open Access Journals (Sweden)

    Denys eSampol

    2013-05-01

    Full Text Available Glucose is the major energetic substrate for the brain but evidence has accumulated during the last 20 years that lactate produced by astrocytes could be an additional substrate for neurons. However, little information exists about this lactate shuttle in vivo in activated and awake animals. We designed an experiment in which the cortical barrel field (S1BF was unilaterally activated during infusion of both glucose and lactate (alternatively labeled with 13C in rats. At the end of stimulation (1h, both S1BF areas were removed and analyzed by HR-MAS NMR spectroscopy to compare glucose and lactate metabolism in the activated area versus the non-activated one. In combination with microwave irradiation, HR-MAS spectroscopy is a powerful technical approach to study brain lactate metabolism in vivo.Using in vivo 14C-2-deoxyglucose and autoradiography, we confirmed that whisker stimulation was effective since we observed a 40% increase in glucose uptake in the activated S1BF area compared to the ipsilateral one.We first determined that lactate observed on spectra of biopsies did not arise from post-mortem metabolism. 1H-NMR data indicated that during brain activation, there was an average 2.4-fold increase in lactate content in the activated area. When [1-13C]glucose+lactate were infused, 13C-NMR data showed an increase in 13C-labeled lactate during brain activation, as well as an increase in lactate C3-specific enrichment. This result demonstrates that the increase in lactate observed on 1H-NMR spectra originates from newly synthesized lactate from the labeled precursor ([1-13C]glucose. It also shows that this additional lactate does not arise from an increase in blood lactate uptake since it would otherwise be unlabeled. These results are in favor of intracerebral lactate production during brain activation in vivo, which could be a supplementary fuel for neurons.

  13. Intrinsic Proton NMR Studies of Mg(OH)2 and Ca(OH)2

    Science.gov (United States)

    Itoh, Yutaka; Isobe, Masahiko

    2016-09-01

    We studied the short proton free induction decay signals and the broad 1H NMR spectra of Mg(OH)2 and Ca(OH)2 powders at 77-355 K and 42 MHz using pulsed NMR techniques. Using a Gaussian-type back extrapolation procedure for the obscured data of the proton free induction decay signals, we obtained more precise values of the second moments of the Fourier-transformed broad NMR spectra than those in a previous report [Y. Itoh and M. Isobe, http://doi.org/10.7566/JPSJ.84.113601, J. Phys. Soc. Jpn. 84, 113601 (2015)] and compared with the theoretical second moments. The decrease in the second moment could not account for the large decrease in the magnitude of the intrinsic proton spin-lattice relaxation rate 1/T1 from Mg(OH)2 to Ca(OH)2. The analysis of 1/T1 ∝ exp(-Eg/kBT) with Eg ˜ 0.01 eV points to a local hopping mechanism, and that of 1/T1 ∝ Tn with n ˜ 0.5 points to an anharmonic rattling mechanism.

  14. 1D and 2D ~1H NMR studies on bisantrene complexes with short DNA oligomers

    Institute of Scientific and Technical Information of China (English)

    姚世杰; WILSON.W.David

    1995-01-01

    The binding of bisantrene to four DNA tetramers,d(CGCG)2,d(GCGC)2,d(CATG)2,and d(GTAC)2,was investigated by 1D and 2D NMR spectroscopy.Bisantrene is.a well knownanticancer drug and has been used clinically for years.DNA is believed to be one of its cellular targets.Re-suits from both ID and 2D 1H NMR are in agreement with an intercalation binding mode of bisantrene withthe four DNA tetramers in this study.The results further indicate that a threading intercalation birdingmode,in which one bisantrene side chain is in the minor groove and the other in the major groove of DNA,is preferred.The NMR results also suggest that bisantrene prefers binding at pyrimidine-(3’,5’)-purineintercalation sequences rather than at purine-(3’,5’)-pyrimidine sequences.The intramolecular andintermolecular NOE contacts of bisantrene-DNA tetramer complexes indicate that a C2’-endo uniform sugarpucker,rather than a mixed sugar conformation,is preferred by the intercalation site of both the 5’-(TA)-3’and the 5’-(CG)-3’ binding steps.

  15. Solution NMR study of the yeast cytochrome c peroxidase: cytochrome c interaction

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, Alexander N., E-mail: ovolkov@vub.ac.be; Nuland, Nico A. J. van [Vrije Universiteit Brussel, Jean Jeener NMR Centre, Structural Biology Brussels (Belgium)

    2013-07-15

    Here we present a solution NMR study of the complex between yeast cytochrome c (Cc) and cytochrome c peroxidase (CcP), a paradigm for understanding the biological electron transfer. Performed for the first time, the CcP-observed heteronuclear NMR experiments were used to probe the Cc binding in solution. Combining the Cc- and CcP-detected experiments, the binding interface on both proteins was mapped out, confirming that the X-ray structure of the complex is maintained in solution. Using NMR titrations and chemical shift perturbation analysis, we show that the interaction is independent of the CcP spin-state and is only weakly affected by the Cc redox state. Based on these findings, we argue that the complex of the ferrous Cc and the cyanide-bound CcP is a good mimic of the catalytically-active Cc-CcP compound I species. Finally, no chemical shift perturbations due to the Cc binding at the low-affinity CcP site were observed at low ionic strength. We discuss possible reasons for the absence of the effects and outline future research directions.

  16. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies

    Science.gov (United States)

    Smith, Albert A.; Corzilius, Björn; Bryant, Jeffrey A.; DeRocher, Ronald; Woskov, Paul P.; Temkin, Richard J.; Griffin, Robert G.

    2012-10-01

    We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz (1H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE011 resonator acts as both an NMR coil and microwave resonator, and a double balanced (1H, 13C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = 1/2 electron spins, 100 kHz on 1H, and 50 kHz on 13C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (⩾3 T).

  17. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies.

    Science.gov (United States)

    Smith, Albert A; Corzilius, Björn; Bryant, Jeffrey A; DeRocher, Ronald; Woskov, Paul P; Temkin, Richard J; Griffin, Robert G

    2012-10-01

    We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz ((1)H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE(011) resonator acts as both an NMR coil and microwave resonator, and a double balanced ((1)H, (13)C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S=1/2 electron spins, 100 kHz on (1)H, and 50 kHz on (13)C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (≥3 T).

  18. Unilateral NMR, 13C CPMAS NMR spectroscopy and micro-analytical techniques for studying the materials and state of conservation of an ancient Egyptian wooden sarcophagus.

    Science.gov (United States)

    Proietti, Noemi; Presciutti, Federica; Di Tullio, Valeria; Doherty, Brenda; Marinelli, Anna Maria; Provinciali, Barbara; Macchioni, Nicola; Capitani, Donatella; Miliani, Costanza

    2011-03-01

    A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV-XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix. This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood and the presence of organic substances by (13)C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical microscopy (OM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Raman and surface enhanced (resonance) Raman spectroscopy (SERS/SERRS), infrared and GC-MS techniques, evidencing original components such as clay minerals, Egyptian green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy.

  19. Synthesis, GC-EIMS, ~1H NMR, ~(13)C NMR, Mechanistic and Thermal Studies of o-Xylylene-α,α'-bis(triphenylphosphinebromide)

    Institute of Scientific and Technical Information of China (English)

    Muddasir Hanif; LU Ping; XU Hai; TIAN Zhi-cheng; YANG Bing; WANG Zhi-ming; TIAN Lei-lei; XU Yuan-ze; XIE Zeng-qi; MA Yu-guang

    2009-01-01

    Organophosphorous compounds containing phosphorus as an integral part have been widely used in industry, organic synthesis and optoelectronics. o-Xylylene-α,α'-bis(triphenylphosphinebromide)(OXBTPPB) is a facile reagent to convert o-quinones(e.g., 9,10-phenanthrenequinone) into polycyclic aromatic hydrocarbons(PAHs). Herein lies an improved synthetic route to OXBTPPB. The resultant was carefully characterized with GC-EIMS, ~1H NMR, ~(13)C NMR, spectroscopic techniques. The EIMS shows characteristic peaks at m/z=262.4, 183.3, 108.2, 77.1 attributed to the [C_(18)H_(15)P]~+, [C_(18)H_8P]~+, [C_6H_5P]~+, [C_6H_5]~+ ions, respectively. The 1H and ~(13)C NMR spectrum shows well resolved peaks and all the hydrogens and carbons were well-assigned via a combined study of ~1H-~1H COSY, HMBC, and HMQC experiments. The mechanism for the formation of OXBTPPB was proposed based on literature and obtained experimental data. Meanwhile, the thermal stability of OXBTPPB was evaluated with TGA analysis, and an onset decomposition temperature(T_d) was recorded at 323.6℃.

  20. Evaluation of microlithographic performance of `deep UV’ resists: Synthesis, and 2D NMR studies on alternating `high ortho’ novolak resins

    Indian Academy of Sciences (India)

    Maneesh Sharma; Anant A Naik; P Raghunathan; S V Eswaran

    2012-03-01

    Lithographic evaluation of a `deep UV’ negative photoresist is discussed along with the synthesis of an alternating `high-ortho’ novolak resin. 2-D NMR studies (COSY, NOESY, HSQC, HMBC) on this resin are also discussed.

  1. Insight into the protonation and K(I)-interaction of the inositol 1,2,3-trisphosphate as provided by 31P NMR and theoretical calculations

    Science.gov (United States)

    Veiga, Nicolás; Torres, Julia; González, Gabriel; Gómez, Kerman; Mansell, David; Freeman, Sally; Domínguez, Sixto; Kremer, Carlos

    2011-02-01

    Animal cells contain a pool of inositol phosphates whose biological function is still under current investigation. Ins(1,2,3) P3 is probably an important safe chelator of iron cations not strongly bound to proteins. In order to clarify its biological functions, Ins(1,2,3) P3 chemistry under physiological conditions must be completely elucidated. The protonation and complexation behaviour of Ins(1,2,3) P3 has been recently studied under these conditions by potentiometry. Under simulated physiological conditions it forms the protonated species H 2L 4- and H 3L 3-. The presence of high concentrations of potassium in intracellular compartments causes the formation of two predominant Ins(1,2,3) P3 complexes: [K(HL)] 4- and [K(H 2L)] 3-, in the absence of iron. In this work we expand part of this macroscopic knowledge to the inframolecular level, by 31P NMR measurements and focusing on the protonation and complexation of this biologically relevant molecule to potassium. We complete this study with theoretical calculations which lead us to predict the geometries of every form of the ligand and their relative stabilities. The influence of the ring conformation in protonated and complexed forms is also discussed.

  2. A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative using NMR spectroscopy techniques.

    Science.gov (United States)

    Hamzah, Rosniza; Bakar, Mohamad Abu; Khairuddean, Melati; Mohammed, Issam Ahmed; Adnan, Rohana

    2012-09-12

    A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative was carried out using NMR spectroscopy techniques. The overlapping (1)H-NMR signals of ENR-50 at δ 1.56, 1.68-1.70, 2.06, 2.15-2.17 ppm were successfully assigned. In this work, the C=S and quaternary carbon of cyclic dithiocarbonate. All other (1)H- and (13)C-NMR chemical shifts of the derivative remain unchanged with respect to the ENR-50.

  3. Neuroprotective effects of caffeine in MPTP model of Parkinson's disease: A (13)C NMR study.

    Science.gov (United States)

    Bagga, Puneet; Chugani, Anup N; Patel, Anant B

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons with an accompanying neuroinflammation leading to loss of dopamine in the basal ganglia. Caffeine, a well-known A2A receptor antagonist is reported to slow down the neuroinflammation caused by activated microglia and reduce the extracellular glutamate in the brain. In this study, we have evaluated the neuroprotective effect of caffeine in the MPTP model of PD by monitoring the region specific cerebral energy metabolism. Adult C57BL6 mice were treated with caffeine (30 mg/kg, i.p.) 30 min prior to MPTP (25 mg/kg, i.p.) administration for 8 days. The paw grip strength of mice was assessed in order to evaluate the motor function after various treatments. For metabolic studies, mice were infused with [1,6-(13)C2]glucose, and (13)C labeling of amino acids was monitored using ex vivo(1)H-[(13)C]-NMR spectroscopy. The paw grip strength was found to be reduced following the MPTP treatment. The caffeine pretreatment showed significant protection against the reduction of paw grip strength in MPTP treated mice. The levels of GABA and myo-inositol were found to be elevated in the striatum of MPTP treated mice. The (13)C labeling of GluC4, GABAC2 and GlnC4 from [1,6-(13)C2]glucose was decreased in the cerebral cortex, striatum, olfactory bulb, thalamus and cerebellum suggesting impaired glutamatergic and GABAergic neuronal activity and neurotransmission of the MPTP treated mice. Most interestingly, the pretreatment of caffeine maintained the (13)C labeling of amino acids to the control values in cortical, olfactory bulb and cerebellum regions while it partially retained in striatal and thalamic regions in MPTP treated mice. The pretreatment of caffeine provides a partial neuro-protection against severe striatal degeneration in the MPTP model of PD.

  4. Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, (2)H NMR, and (31)P NMR spectroscopy.

    Science.gov (United States)

    Pötzschner, B; Mohamed, F; Bächer, C; Wagner, E; Lichtinger, A; Bock, D; Kreger, K; Schmidt, H-W; Rössler, E A

    2017-04-28

    We investigate the secondary (β-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of (2)H and (31)P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a β-relaxation (β1 (SBC) and β2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the β-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical (31)P NMR echo spectra of the β2-process, very similar spectral features are observed for the (deuterated) SBC component by (2)H NMR, in addition to its "own" β1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τβ2 are the same. Furthermore, T1(T) of TPP in the temperature region of the β2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the β-process introduced by one component are essentially independent of the second component. Finally, at cTPP

  5. Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, 2H NMR, and 31P NMR spectroscopy

    Science.gov (United States)

    Pötzschner, B.; Mohamed, F.; Bächer, C.; Wagner, E.; Lichtinger, A.; Bock, D.; Kreger, K.; Schmidt, H.-W.; Rössler, E. A.

    2017-04-01

    We investigate the secondary (β-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of 2H and 31P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a β-relaxation (β1 (SBC) and β2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the β-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical 31P NMR echo spectra of the β2-process, very similar spectral features are observed for the (deuterated) SBC component by 2H NMR, in addition to its "own" β1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τβ2 are the same. Furthermore, T1(T) of TPP in the temperature region of the β2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the β-process introduced by one component are essentially independent of the second component. Finally, at cTPP ≤ 20% one

  6. Teaching NMR Using Online Textbooks

    Directory of Open Access Journals (Sweden)

    Joseph P. Hornak

    1999-12-01

    Full Text Available Nuclear magnetic resonance (NMR spectroscopy has almost become an essential analytical tool for the chemist. High-resolution one- and multi-dimensional NMR, timedomain NMR, and NMR microscopy are but a few of the NMR techniques at a chemist's disposal to determine chemical structure and dynamics. Consequently, even small chemistry departments are finding it necessary to provide students with NMR training and experience in at least some of these techniques. The hands-on experience is readily provided with access to state-of-the-art commercial spectrometers. Instruction in the principles of NMR is more difficult to achieve as most instructors try to teach NMR using single organic or analytical chemistry book chapters with static figures. This paper describes an online textbook on NMR spectroscopy called The Basics of NMR (http://www.cis.rit.edu/htbooks/nmr/ suitable for use in teaching the principles of NMR spectroscopy. The book utilizes hypertext and animations to present the principles of NMR spectroscopy. The book can be used as a textbook associated with a lecture or as a stand-alone teaching tool. Conference participants are encouraged to review the textbook and evaluate its suitability for us in teaching NMR spectroscopy to undergraduate chemistry majors.

  7. Conformational analysis, UV-VIS, MESP, NLO and NMR studies of 6-methoxy-1,2,3,4-tetrahydronaphthalene.

    Science.gov (United States)

    Arivazhagan, M; Kavitha, R; Subhasini, V P

    2014-07-15

    The detailed HF and B3LYP/6-311++G(d,p) comparative studies on the complete FT-IR and FT-Raman spectra of 6-methoxy-1,2,3,4-tetrahydronaphthalene [MTHN] have been studied. In view of the special properties and uses, the present investigation has been undertaken to provide a satisfactorily vibrational analysis of 6-methoxy-1,2,3,4-tetrahydronaphthalene. Therefore, a thorough Raman, IR, molecular electrostatic potential (MESP), non-linear optical (NLO) properties, UV-VIS, HOMO-LUMO and NMR spectroscopic investigation are reported complemented by B3LYP theoretical predictions with basis set 6-311++G(d,p) to provide novel insight on vibrational assignments and conformational stability of MTHN. Potential energy surface scans (PES) of the CH3 group are undertaken to shed light on the rather complicated conformational interchanges in the compound under investigation.

  8. Hexameric Capsules Studied by Magic Angle Spinning Solid-State NMR Spectroscopy: Identifying Solvent Molecules in Pyrogallol[4]arene Capsules.

    Science.gov (United States)

    Avram, Liat; Goldbourt, Amir; Cohen, Yoram

    2016-01-18

    Powders of pyrogallol[4]arene hexamers were produced by evaporation from organic solvents and were studied, for the first time, by magic angle spinning solid-state NMR (MAS ssNMR). Evaporation selectively removed non-encapsulated solvent molecules leaving stable hexameric capsules encapsulating solvent molecules. After exposure of the powder to solvent vapors, (1)H/(13)C heteronuclear correlation MAS ssNMR experiments were used to assign the signals of the external and encapsulated solvent molecules. The formed capsules were stable for months and the process of solvent encapsulation was reversible. According to the ssNMR experiments, the encapsulated solvent molecules occupy different sites and those sites differ in their mobility. The presented approach paves the way for studying guest exchange, guest affinity, and gas storage in hexamers of this type in the solid state.

  9. NMR-based metabolomics approach to study the toxicity of lambda-cyhalothrin to goldfish (Carassius auratus)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Minghui [State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009 (China); Wang, Junsong, E-mail: wang.junsong@gmail.com [Center for Molecular Metabolism, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei Street, Nanjing 210094 (China); Lu, Zhaoguang; Wei, Dandan; Yang, Minghua [State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009 (China); Kong, Lingyi, E-mail: cpu_lykong@126.com [State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009 (China)

    2014-01-15

    Highlights: •A goldfish model was established to investigate the toxicity of lambda-cyhalothrin (LCT) exposure on multiple organs. •NMR based metabolomics approach were firstly used to provide a global view of the toxicity of LCT. •LCT induced neurotransmitters and osmoregulatory imbalances, oxidative stress, energy and amino acid metabolic disorders. •Glutamate–glutamine–GABA axis as a potential target for LCT toxicity was first found. -- Abstract: In this study, a {sup 1}H nuclear magnetic resonance (NMR) based metabolomics approach was applied to investigate the toxicity of lambda-cyhalothrin (LCT) in goldfish (Carassius auratus). LCT showed tissue-specific damage to gill, heart, liver and kidney tissues of goldfish. NMR profiling combined with statistical methods such as orthogonal partial least squares discriminant analysis (OPLS-DA) and two-dimensional statistical total correlation spectroscopy (2D-STOCSY) was developed to discern metabolite changes occurring after one week LCT exposure in brain, heart and kidney tissues of goldfish. LCT exposure influenced levels of many metabolites (e.g., leucine, isoleucine and valine in brain and kidney; lactate in brain, heart and kidney; alanine in brain and kidney; choline in brain, heart and kidney; taurine in brain, heart and kidney; N-acetylaspartate in brain; myo-inositol in brain; phosphocreatine in brain and heart; 2-oxoglutarate in brain; cis-aconitate in brain, and etc.), and broke the balance of neurotransmitters and osmoregulators, evoked oxidative stress, disturbed metabolisms of energy and amino acids. The implication of glutamate–glutamine–gamma-aminobutyric axis in LCT induced toxicity was demonstrated for the first time. Our findings demonstrated the applicability and potential of metabolomics approach for the elucidation of toxicological effects of pesticides and the underlying mechanisms, and the discovery of biomarkers for pesticide pollution in aquatic environment.

  10. (1)H NMR Study of the solution structure of sarafotoxin-S6b.

    Science.gov (United States)

    Aumelas, A; Chiche, L; Mahe, E; Le-Nguyen, D; Sizun, P; Berthault, P; Perly, B

    1991-01-01

    Sarafotoxin-S6b has been synthesized and studied by (1)H NMR in 50 50 acetonitrile/water mixture. All spin systems were identified and assigned with the aid of 2D experiments. On the basis of these data, a 3D structure of sarafotoxin is proposed and compared to that of [Nle(7)]endothelin obtained in the same conditions. From this study, it appeared that sarafotoxin-S6b and [Nle(7)]endothelin roughly share the same 3D structure, the main differences being located in the 4-7 loop bearing the sequence variation.

  11. Proliferating cell nuclear antigen (PCNA interactions in solution studied by NMR.

    Directory of Open Access Journals (Sweden)

    Alfredo De Biasio

    Full Text Available PCNA is an essential factor for DNA replication and repair. It forms a ring shaped structure of 86 kDa by the symmetric association of three identical protomers. The ring encircles the DNA and acts as a docking platform for other proteins, most of them containing the PCNA Interaction Protein sequence (PIP-box. We have used NMR to characterize the interactions of PCNA with several other proteins and fragments in solution. The binding of the PIP-box peptide of the cell cycle inhibitor p21 to PCNA is consistent with the crystal structure of the complex. A shorter p21 peptide binds with reduced affinity but retains most of the molecular recognition determinants. However the binding of the corresponding peptide of the tumor suppressor ING1 is extremely weak, indicating that slight deviations from the consensus PIP-box sequence dramatically reduce the affinity for PCNA, in contrast with a proposed less stringent PIP-box sequence requirement. We could not detect any binding between PCNA and the MCL-1 or the CDK2 protein, reported to interact with PCNA in biochemical assays. This suggests that they do not bind directly to PCNA, or they do but very weakly, with additional unidentified factors stabilizing the interactions in the cell. Backbone dynamics measurements show three PCNA regions with high relative flexibility, including the interdomain connector loop (IDCL and the C-terminus, both of them involved in the interaction with the PIP-box. Our work provides the basis for high resolution studies of direct ligand binding to PCNA in solution.

  12. The aluminium effect on the structure of silico-phosphate glasses studied by NMR and FTIR

    Science.gov (United States)

    Sitarz, Maciej; Fojud, Zbigniew; Olejniczak, Zbigniew

    2009-04-01

    Silico-phosphate glasses of NaCaPO 4-SiO 2 and NaCaPO 4-AlPO 4-SiO 2 system have been the subject of the presented investigations. Glasses of these systems are the basis for the preparation of glassy-crystalline biomaterials [R.D. Rawlings, Clin. Mater. 14 (1993) 155]. Detailed knowledge of the precursor glass structure is necessary for proper design of the glassy-crystalline biomaterials preparation procedure. Since there is no long-range ordering in glasses, spectroscopic methods which make it possible to study the short range ordering should be applied. MIR studies carried out in the work have allowed to establish that the glasses of the systems studied show domain composition [L.L. Hench, R.J. Splinter, T.K. Greenlee, W.C. Allen, J. Biol. Res. Symp. 2 (1971) 117; L.L. Hench, R.J. Splinter, W.C. Allen, T.K. Greenlee, J. Biol. Res. 5 (1972) 117]. Domain structure is close to that of the corresponding crystalline phases. It has been shown that even small amount of aluminium in the glass (5 mol.% of AlPO 4) significantly influences both, its texture (microscopic and EDX studies) and its structure (spectroscopic studies). 27Al NMR investigations have made it possible to establish unequivocally that aluminium occurs exclusively in tetrahedral coordination, i.e. it is involved in the formation of glass framework. Presence of aluminium results in significant changes in the [SiO 4] 4- and [PO 4] 3- tetrahedra environment which is reflected in 23Na, 31P and 29Si NMR spectra. Changes in the shapes and positions of the bands in the NMR spectra of glasses belonging to the NaCaPO 4-AlPO 4-SiO 2 system confirm great influence of aluminium on silico-phosphate glasses structure.

  13. A NMR reverse diffusion filter for the simplification of spectra of complex mixtures and the study of drug receptor interactions.

    Science.gov (United States)

    Vega-Vázquez, M; Cobas, J C; Oliveira de Sousa, F F; Martin-Pastor, M

    2011-08-01

    A reverse diffusion filter NMR experiment (Drev) is proposed for the study of small molecules in binding with macromolecules. The filtering efficiency of Drev to eliminate the signals of the macromolecule is shown to be superior to conventional transverse relaxation filters at least for macromolecules containing a significant fraction of flexible residues. The Drev filter was also a useful complement for ligand-based NMR screening in combination with saturation transfer difference experiments.

  14. The Three Dimensional Structure and Interaction Studies of HCV p7 in DHPC by Solution NMR

    Science.gov (United States)

    Cook, Gabriel A.; Dawson, Lindsay A.; Tian, Ye; Opella, Stanley J.

    2013-01-01

    Hepatitis C Virus (HCV) protein p7 plays an important role in the assembly and release of mature virus particles. This small 63-residue membrane protein has been shown to induce channel activity, which may contribute to its functions. p7 is highly conserved throughout the entire range of HCV genotypes, which contributes to making p7 a potential target for anti-viral drugs. The secondary structure of p7 from the J4 genotype and the tilt angles of the helices within bilayers have been previously characterized by NMR. Here we describe the three-dimensional structure of p7 in short chain phospholipid (DHPC) micelles, which provide a reasonably effective membrane-mimicking environment that is compatible with solution NMR experiments. Using a combination of chemical shifts and residual dipolar couplings we determined the structure of p7 using an implicit membrane potential combining both CS-Rosetta decoys and Xplor-NIH refinement. The final set of structures has a backbone RMSD of 2.18 Å. Molecular dynamic simulations in NAMD indicate that several side chain interactions might be taking place, and that these could affect the dynamics of the protein. In addition to probing the dynamics of p7, several drug-protein and protein-protein interactions were evaluated. Established channel-blocking compounds such as amantadine, hexamethylene amiloride (HMA), and long alkyl-chain iminosugar derivatives inhibit the ion channel activity of p7. It has also been shown that the protein interacts with the HCV non-structural protein 2 (NS2) at the endoplasmic reticulum, and that this interaction may be important for the infectivity of the virus. Changes in the chemical shift frequencies of solution NMR spectra identify the residues taking part in these interactions. PMID:23841474

  15. An explanation for the high stability of polycarboxythiophenes in photovoltaic devices—A solid-state NMR dipolar recoupling study

    DEFF Research Database (Denmark)

    Bierring, M.; Nielsen, J.S.; Siu, Ana

    2008-01-01

    observed in photovoltaic devices employing polythiophene substituted with carboxylic-acid moieties under oxygen free conditions. H-1 and C-13 solid-state NMR, IR, and ESR spectroscopy of unmodified and isotopically labeled polythiophenes were studied. Distances between the isotopically labeled carboxylic...... acid carbon atoms were measured by C-13 solid-state magic-angle-spinning (MAS) NMR using symmetry-based double-quantum (2Q) dipolar recoupling. This revealed the presence of C-13-C-13 distances of 3.85 angstrom, which correspond to the C-C distance in hydrogen-bonded carboxylic acid dimers. In spite...... of the presence of carboxylic groups in the polymer as demonstrated by C-13 CP/MAS NMR and IR spectroscopy, the absence of carboxylic protons in solid state H-1 NMR spectra indicate that they are mobile. We link the extraordinary stability of this system to the rigid nature, cross-linking through a hydrogen...

  16. Applications of Solid State NMR to the Study of Molecular Structure

    Science.gov (United States)

    Curtis, Ronald Dean

    This thesis illustrates several applications of dilute spin I = 1over2 solid state nmr spectroscopy to the study of molecular structure in systems of chemical interest. Specifically, the compounds studied include benzylideneaniline and several related imines, the first stable iminophosphenium cation containing a N,P triple bond and several tetracyclines. The first two applications describe the use of dipolar-chemical shift nmr of "isolated" spin-pairs to fully characterize chemical shift tensors. For example, the carbon and nitrogen shift tensors of the C=N linkage of the Schiff base benzylideneaniline have been completely specified. The most shielded principal component of both carbon and nitrogen shift tensors is approximately perpendicular to the imine fragment. For the imine carbon, the intermediate component of the shift tensor is directed approximately along the C=N bond whereas the corresponding component of the nitrogen shift tensor is oriented along the direction of the nitrogen lone pair. Examination of the nitrogen chemical shift parameters for several related imines suggests that variations in the least shielded principal component are mainly responsible for changes in the nitrogen shieldings in the imine system. For the N,P moiety of the iminophosphenium cation, the most shielded principal component of both nitrogen and phosphorus tensors is oriented along the N,P bond axis. Comparison of both shift tensors with those of related compounds suggests that the electronic environment surrounding the N,P moiety is similar to other systems containing a formal triple bond. The final application section demonstrates the utility of high-resolution ^{13} C and ^{15}N cp/mas nmr for studying the molecular structure of solid tetracycline antibiotics. Comparison of ^{15} C chemical shifts in the solid state to those determined in (CD_3)_2SO solutions indicates for the first time that the structural integrity of the A ring of the tetracyclines is maintained in

  17. In vivo NMR study of yeast fermentative metabolism in the presence of ferric irons

    Indian Academy of Sciences (India)

    Maso Ricci; Silvia Martini; Claudia Bonechi; Daniela Braconi; Annalisa Santucci; Claudio Rossi

    2011-03-01

    Mathematical modelling analysis of experimental data, obtained with in vivo NMR spectroscopy and 13C-labelled substrates, allowed us to describe how the fermentative metabolism in Saccharomyces cerevisiae, taken as eukaryotic cell model, is influenced by stress factors. Experiments on cellular cultures subject to increasing concentrations of ferric ions were conducted in order to study the effect of oxidative stress on the dynamics of the fermentative process. The developed mathematical model was able to simulate the cellular activity, the metabolic yield and the main metabolic fluxes occurring during fermentation and to describe how these are modulated by the presence of ferric ions.

  18. Unconventional superconductivity in PuRhGa{sub 5}: Ga NMR/NQR study

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, H. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)]. E-mail: sakai.hironori@jaea.go.jp; Tokunaga, Y. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Fujimoto, T. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Kambe, S. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Walstedt, R.E. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Yasuoka, H. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Aoki, D. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Homma, Y. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Yamamoto, E. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Nakamura, A. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Shiokawa, Y. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nakajima, K. [Department of Nuclear Energy System, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Arai, Y. [Department of Nuclear Energy System, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Matsuda, T.D. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Haga, Y. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Onuki, Y. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2006-05-01

    {sup 69,71}Ga NMR/NQR studies have been performed on a single crystal of the transuranium superconductor PuRhGa{sub 5} with T{sub c}{approx}9K. The spin-lattice relaxation rate 1/T{sub 1} reveals that PuRhGa{sub 5} is an unconventional superconductor having an anisotropic superconducting gap. Moreover, Korringa behavior (1/T{sub 1}T=const.) is observed in the normal state below {approx}30K. This result suggests that the superconductivity sets in after the formation of a Fermi liquid state in this compound.

  19. Exfoliation Dynamics of Laponite Clay in Aqueous Suspensions Studied by NMR Relaxometry

    Directory of Open Access Journals (Sweden)

    Anastasia Karpovich

    2016-06-01

    Full Text Available The interaction between Laponite and other constituents in complex systems greatly depends on its available surface area. We report a study of exfoliation dynamics of Laponite in aqueous suspensions by NMR relaxometry. It showed that Laponite particles exfoliate to the same extent in a concentration range of 0.5-3% w/w. Faster increase of specific wetted surface area of Laponite particles in more concentrated suspensions suggests faster exfoliation of disc-shaped Laponite platelets from the initial layered structure.

  20. Conformational Study of 8-C-glucosyl-prunetin by Dynamic NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin,isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-I" gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.

  1. NMR Studies of a New Binding Mode of the Amino Acid Esters by Porphyrinatozinc(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The binding mode of the amino acid ethyl esters(guest) by 5-(2-carboxylphenyl)-10,15,20-triphenylporphyrinatozinc(Ⅱ)(host 1) was studied by means of 1H NMR spectra. The binding mode is the hydrogen-bonding between the amino group of the guest and the carboxyl group of host 1 plus the coordination between the zinc atom of porphyrinatozinc(Ⅱ) and the carbonyl group of the guest. This is a novel binding mode of the metalloporphyrin to amino acid derivatives.

  2. 1H NMR study of fermented cocoa (Theobroma cacao L.) beans.

    Science.gov (United States)

    Caligiani, Augusta; Acquotti, Domenico; Cirlini, Martina; Palla, Gerardo

    2010-12-08

    This study reports for the first time the metabolic profile of cocoa (Theobroma cacao L.) beans using the (1)H NMR technique applied to polar extracts of fermented cocoa beans. The simultaneous detection and quantification of amino acids, polyalcohols, organic acids, sugars, methylxanthines, catechins, and phenols were obtained by assigning the major signals of the spectra for different varieties of cocoa beans (Forastero, Criollo, and Trinitario) from different countries (Ecuador, Ghana, Grenada, and Trinidad). The data set obtained, representative of all classes of soluble compounds of cocoa, was useful to characterize the fermented cocoa beans as a function of the variety and geographic origin.

  3. Conformational Study of 8—C—glucosyl—prunetin by Dynamic NMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    PeiChengZHANG; YingHongWANG; 等

    2002-01-01

    By means of variable temperature NMR spectra,conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C(sp3)-C(sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1″ gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.

  4. [1H-NMR studies of the ACTH-like immunoregulatory peptides].

    Science.gov (United States)

    Khristoforov, V S; Kutyshenko, V P; Abramov, V M; Zav'ialov, V P

    1997-01-01

    A comparative study of the conformational and dynamics properties of the ACTH-like linear peptides, sequences of which correspond to amino acid residues 11-20 of the heavy chain of human immunoglobulin G1 Eu, residues 78-85 of human pro-interleukin-1 alpha and site 10-18 of human ACTH, was performed in aqueous solution and dimethylsulfoxide by 1H-NMR spectroscopy at 400 MHz. The peptides were shown to possess an unordered unfolded flexible conformation in aqueous solution. The revealed structural and dynamic features of the peptides are discussed together with biological activity of this class of compounds.

  5. NMR studies of organic liquids confined in mesoporous materials: (1) Pore size distribution and (2) Phase behaviour and dynamic studies in restricted geometry

    Energy Technology Data Exchange (ETDEWEB)

    Foerland, Kjersti

    2005-07-01

    In the thesis NMR spectroscopy is used for studying liquids confined in various porous materials. In the first part, pore size distributions of mesoporous silicas and controlled pore glasses were determined by measuring the 1H NMR signal from the non-frozen fraction of the confined liquid as a function of temperature, using benzene, acetonitrile and HMDS as probe molecules. In the second part, the molecular dynamics of acetonitrile, hexamethyldisilane, cyclohexane and cyclopentane confined in mesoporous materials were studied as a function of temperature. 6 papers are included with titles: 1) Pore-size determination of mesoporous materials by 1H NMR spectroscopy. 2) Pore-size distribution in mesoporous materials as studied by 1H NMR. 3) Dynamic 1H and 2H NMR investigations of acetonitrile confined in porous silica. 4) NMR investigations of hexamethyldisilane confined in controlled pore glasses: Pore size distribution and molecular dynamics studies. 5) 1H and 2H NMR studies of cyclohexane nano crystals in controlled pore glasses. 6) 1H NMR relaxation and diffusion studies of cyclohexane and cyclopentane confined in MCM-41.

  6. NMR and NQR studies of quadrupolar effects in glasses and polycrystals with half-integer spins

    Science.gov (United States)

    Orengo-Aviles, Moises

    NMR and NQR techniques have been used in the present study to investigate glasses and polycrystalline compounds containing nuclei with half-integer spins such as: sp{11}B, sp{23}Na, sp{45}Sc, and sp{93}Nb. The low field ({˜}1.2{-}1.5 Tesla) continuous wave (CW) NMR experiments were performed using the Non-Adiabatic Superfast Passage (NASP) or the slow passage methods. A BRUKER MSL 300 pulsed NMR spectrometer was used for the high field (7.1 Tesla) studies. The CW NQR experiments at room and liquid nitrogen temperature were carried out on a home built Robinson-type spectrometer. Using pulsed NMR the sp{45}Sc response from the glass system CaO-Bsb2Osb3-Scsb2Osb3, yielded a first-order quadrupolar interaction with eta=0 and Qsb{cc}≈617 kHz. A new Sc site with Qsb{cc}=23.44 MHz and eta=0 was found in polycrystalline Scsb2Osb3 and it was confirmed by NQR. Employing the NASP method it was found that the fraction of four-coordinated (Nsb4) boron atoms in the alkali thioborate (Nasb2S-Bsb2Ssb3) glass system follows a 3x/(1 - x) relationship for x≤0.15, where x is the molar fraction of Nasb2S in the glass. For the NQR spectra the 10% Nasb2S content glass exhibited a broader NQR resonance than the NQR resonance for pure v-Bsb2Ssb3. The additional width was attributed to responses of BSsb3 units whose Qsb{cc} values differ somewhat from the BSsb3 units in the pure vitreous Bsb2Ssb3. The CW NASP method was used to study the sp{23}Na response in the Nasb2O*2SiOsb2 glass, heat treated in three ways: annealed, slow cooled and splat quenched. Subjecting the glass to rapid cooling will produce an increased range of values for the components of the electric field gradient (EFG), and, hence an increased range of values for Qsb{cc} and eta. This was observed for the slow cooled sample when compared with the annealed glass. The effect should be seen also from the slow cooled to the splat quenched sample, but this was not observed. Crystalline sodium disilicate was examined by both

  7. (1)H NMR based metabolomics approach to study the toxic effects of herbicide butachlor on goldfish (Carassius auratus).

    Science.gov (United States)

    Xu, Hua-Dong; Wang, Jun-Song; Li, Ming-Hui; Liu, Yan; Chen, Ting; Jia, Ai-Qun

    2015-02-01

    Butachlor, one of the most widely used herbicides in agriculture, has been reported with high ecotoxicity to aquatic plants and animals. In this study, a (1)H NMR based metabolomics approach combined with histopathological examination and biochemical assays was applied to comprehensively investigate the toxic effects of butachlor on four important organs (gill, brain, liver and kidney) of goldfish (Carassius auratus) for the first time. After 10 days' butachlor exposure at two dosages of 3.2 and 0.64 μmol/L, fish tissues (gill, brain, liver and kidney) and serum were collected. Histopathological inspection revealed severe impairment of gill filaments and obvious cellular edema in livers and kidneys. The increase of glutathione peroxidase (GSH-Px) activity in gill and methane dicarboxylic aldehyde (MDA) level in four tissues reflected the disturbance of antioxidative system in the intoxicated goldfish. Serum lactate dehydrogenase (LDH) activity and creatinine (CRE) level were increased in butachlor exposure groups, suggesting liver and kidney injuries induced by butachlor. Orthogonal signal correction partial least-squares discriminant analysis (OSC-PLS-DA) of NMR profiles disclosed metabolic changes that were related to the toxic effects of butachlor including oxidative stress, disorder of energy metabolism and amino acids metabolism, and disturbance of neurotransmitter balance in butachlor exposed goldfish. This integrated metabolomics approach provided a molecular basis underlying the toxicity of butachlor and demonstrated that metabolomics was a powerful and highly effective approach to elucidate the toxicity and underlying mechanisms of herbicides and pesticides, applicable for their risk assessment.

  8. (1)H NMR-based metabolomics study on repeat dose toxicity of fine particulate matter in rats after intratracheal instillation.

    Science.gov (United States)

    Zhang, Yannan; Hu, Hejing; Shi, Yanfeng; Yang, Xiaozhe; Cao, Lige; Wu, Jing; Asweto, Collins Otieno; Feng, Lin; Duan, Junchao; Sun, Zhiwei

    2017-07-01

    Systemic metabolic effects and toxicity mechanisms of ambient fine particulate matter (PM2.5) remain uncertain. In order to investigate the mechanisms in PM2.5 toxicity, we explored the endogenous metabolic changes and possible influenced metabolic pathways in rats after intratracheal instillation of PM2.5 by using a (1)H nuclear magnetic resonance (NMR)-based metabolomics approach. Liver and kidney histopathology examinations were also performed. Chemical characterization demonstrated that PM2.5 was a complex mixture of elements. Histopathology showed cellular edema in liver and glomerulus atrophy of the PM2.5 treated rats. We systematically analyzed the metabolites changes of serum and urine in rats using (1)H NMR techniques in combination with multivariate statistical analysis. Significantly reduced levels of lactate, alanine, dimethylglycine, creatine, glycine and histidine in serum, together with increased levels of citrate, arginine, hippurate, allantoin and decreased levels of allthreonine, lactate, alanine, acetate, succinate, trimethylamine, formate in urine were observed of PM2.5 treated rats. The mainly affected metabolic pathways by PM2.5 were glycine, serine and threonine metabolism, glyoxylate and dicarboxylate metabolism, citrate cycle (TCA cycle), nitrogen metabolism and methane metabolism. Our study provided important information on assessing the toxicity of PM2.5 and demonstrated that metabolomics approach can be employed as a tool to understand the toxicity mechanism of complicated environmental pollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. NMR and Nqr Study of Atomic Order in Alkali Borate Glasses.

    Science.gov (United States)

    Gravina, Samuel John

    A modified Robinson oscillator circuit was built for the detection of nuclear quadrupole resonance (NQR) in the 200 to 10,000 kHz region. The circuit demonstrates near ideal performance with the detected noise limited only by the sample temperature. The use of computer controlled data acquisition and a carefully designed sample probe allows for the use of an integrating time constant of up to 6 hours. This spectrometer has been used to detect ^{10}B and ^{11 }B NQR in lithium and sodium borate glasses and crystals. In pure boron oxide glass two distinct boron sites are found. By comparing this experiment with previous NMR and Raman spectroscopy studies, one of the sites, which comprises 85% of the total boron, can be attributed to boron atoms in boroxol rings. As sodium is added to the glass the abundance of boroxol rings decreases. At 20 mol% sodium oxide less than 2% of the boron atoms are found in boroxol rings. The dipole-dipole interaction between lithium cations and four-coordinated boron atoms (B_4 units) has been measured. It is found that every B_4 unit has one lithium cation next to it at an average distance of 2.82 A. A comparison with lithium borate crystals shows that diborate groups do not occur in significant quantities. Both high field and low field NMR studies of the boron quadrupole interaction in a B_4 unit also show that diborate groups are not found in the glass. A ^{23}Na and ^6Li NMR MASS study of lithium and sodium borate glasses shows that ^{23 }Na chemical shifts can distinguish sodium cations bound to non-bridging oxygens from sodium cations bound to bridging oxygens. The chemical shifts measured in lithium-sodium borate glasses are identical to those measured in lithium borate or sodium borate glasses, indicating similar alkali-oxygen coordination. A significant narrowing of the ^6Li NMR spectrum in a mixed alkali glass can be understood as a decrease in the entropy of the lithium cations. This result is consistent with the weak

  10. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    Science.gov (United States)

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported.

  11. 29Si NMR study of structural ordering in aluminosilicate geopolymer gels.

    Science.gov (United States)

    Duxson, Peter; Provis, John L; Lukey, Grant C; Separovic, Frances; van Deventer, Jannie S J

    2005-03-29

    A systematic series of aluminosilicate geopolymer gels was synthesized and then analyzed using 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) in combination with Gaussian peak deconvolution to characterize the short-range ordering in terms of T-O-T bonds (where T is Al or Si). The effect of nominal Na2O/(Na2O + K2O) and Si/Al ratios on short-range network ordering was quantified by deconvolution of the 29Si MAS NMR spectra into individual Gaussian peaks representing different Q4(mAl) silicon centers. The deconvolution procedure developed in this work is applicable to other aluminosilicate gel systems. The short-range ordering observed here indicates that Loewenstein's Rule of perfect aluminum avoidance may not apply strictly to geopolymeric gels, although further analyses are required to quantify the degree of aluminum avoidance. Potassium geopolymers appeared to exhibit a more random Si/Al distribution compared to that of mixed-alkali and sodium systems. This work provides a quantitative account of the silicon and aluminum ordering in geopolymers, which is essential for extending our understanding of the mechanical strength, chemical and thermal stability, and fundamental structure of these systems.

  12. Ordering in nematic liquid crystals from NMR cross-polarization studies

    Indian Academy of Sciences (India)

    K V Ramanathan; Neeraj Sinha

    2003-08-01

    The measurement of dipolar couplings between nuclei is a convenient way of obtatining directly liquid crystalline ordering through NMR since the coupling is dependent on the average orientation of the dipolar vector in the magnetic field which also aligns the liquid crystal. However, measurement of the dipolar coupling between a pair of selected nuclei is beset with problems that require special solutions. In this article the use of cross polarization for measuring dipolar couplings in liquid crystals is illustrated. Transient oscillations observed during cross polarization provide the dipolar couplings between essentially isolated nearest neighbour spins which can be extracted for several sites simultaneously by employing two-dimensional NMR techniques. The use of the method for obtaining heteronuclear dipolar couplings and hence the order parameters of liquid crystals is presented. Several modifications to the basic experiment are considered and their utility illustrated. A method for obtaining proton–proton dipolar couplings, by utilizing cross polarization from the dipolar reservoir, is also presented.

  13. Pseudogap and anharmonic phonon behavior in Ba8Ga16Ge30: An NMR study

    Science.gov (United States)

    Sirusi, Ali A.; Ross, Joseph H.

    2016-08-01

    We have performed 69Ga, 71Ga, and 137Ba NMR on Ba8Ga16Ge30, a clathrate semiconductor which has been of considerable interest due to its large figure of merit for thermoelectric applications. In measurements from 4 K to 450 K, we used measurements on the two Ga nuclei to separate the magnetic and electric quadrupole hyperfine contributions and thereby gain information about the metallic and phonon behavior. The results show the presence of a pseudogap in the Ga electronic states within the conduction band, superposed upon a large Ba contribution to the conduction band. Meanwhile the phonon contributions to the Ga relaxation rates are large and increase more rapidly with temperature than typical semiconductors. These results provide evidence for enhanced anharmonicity of the propagative phonon modes over a wide range, providing experimental evidence for enhanced phonon-phonon scattering as a mechanism for the reduced thermal conductivity.

  14. Structural studies of lithium zinc borohydride by neutron powder diffraction, Raman and NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ravnsbaek, D.B. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Frommen, C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Reed, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Filinchuk, Y. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Institute of Condensed Matter and Nanosciences, Universite Catholique de Louvain, 1 Place L. Pasteur, B-1348, Louvain-la-Neuve (Belgium); Sorby, M.; Hauback, B.C. [Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway); Jakobsen, H.J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Book, D. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Besenbacher, F. [Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Skibsted, J. [Instrument Centre for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark); Jensen, T.R., E-mail: trj@chem.au.dk [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C (Denmark)

    2011-09-15

    Research highlights: > Structural study of the first interpenetrated framework hydride, LiZn{sub 2}(BH{sub 4}){sub 5} > Determination of deuterium positions and revision of crystal structure by PND. > Raman spectroscopy confirms the presence of isolated [Zn{sub 2}(BD{sub 4}){sub 5}]-bar complex anions. > Determination of quadrupole coupling parameters and chemical shifts by {sup 11}B MAS NMR. - Abstract: The crystal structure of LiZn{sub 2}(BH{sub 4}){sub 5} is studied in detail using a combination of powder neutron diffraction (PND), Raman spectroscopy, and {sup 11}B MAS NMR spectroscopy on LiZn{sub 2}(BH{sub 4}){sub 5} and LiZn{sub 2}({sup 11}BD{sub 4}){sub 5}. The aim is to obtain detailed structural knowledge of the first interpenetrated framework hydride compound, LiZn{sub 2}(BD{sub 4}){sub 5} which consists of doubly interpenetrated 3D frameworks built from dinuclear complex ions [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} and lithium ions. The positions of the deuterium atoms are determined using Rietveld refinement of the PND data and the orientation of one of the four independent BD{sub 4}{sup -} groups is revised. The current data reveal that the structure of [Zn{sub 2}(BD{sub 4}){sub 5}]{sup -} is more regular than previously reported, as are also the coordinations around the Zn and Li atoms. Both Zn and Li atoms are found to coordinate to the BD{sub 4}{sup -} units via the tetrahedral edges. Some distortion of the angles within the BD{sub 4} units is observed, relative to the expected angles of 109.4 for the ideal tetrahedral coordination. Raman spectroscopy confirms bending and stretching modes from the expected terminal and bridging bidentate BH{sub 4}{sup -} and BD{sub 4}{sup -} units. The {sup 11}B MAS NMR spectrum of the satellite transitions resolves two distinct manifolds of spinning sidebands, which allows estimation of the {sup 11}B quadrupole coupling parameters and isotropic chemical shifts for the four distinct {sup 11}B sites of [Zn{sub 2}(BD

  15. NMR for chemists and biologists

    CERN Document Server

    Carbajo, Rodrigo J

    2013-01-01

    This book offers a concise introduction to the field of nuclear magnetic resonance or NMR. It presents the basic foundations of NMR in a non-mathematical way and provides an overview of both recent and important biological applications of NMR.

  16. Structural studies of bacterial transcriptional regulatory proteins by multidimensional heteronuclear NMR

    Energy Technology Data Exchange (ETDEWEB)

    Volkman, B.F.

    1995-02-01

    Nuclear magnetic resonance spectroscopy was used to elucidate detailed structural information for peptide and protein molecules. A small peptide was designed and synthesized, and its three-dimensional structure was calculated using distance information derived from two-dimensional NMR measurements. The peptide was used to induce antibodies in mice, and the cross-reactivity of the antibodies with a related protein was analyzed with enzyme-linked immunosorbent assays. Two proteins which are involved in regulation of transcription in bacteria were also studied. The ferric uptake regulation (Fur) protein is a metal-dependent repressor which controls iron uptake in bacteria. Two- and three-dimensional NMR techniques, coupled with uniform and selective isotope labeling allowed the nearly complete assignment of the resonances of the metal-binding domain of the Fur protein. NTRC is a transcriptional enhancer binding protein whose N-terminal domain is a {open_quote}receiver domain{close_quote} in the family of {open_quote}two-component{close_quote} regulatory systems. Phosphorylation of the N-terminal domain of NTRC activates the initiation of transcription of aeries encoding proteins involved in nitrogen regulation. Three- and four-dimensional NMR spectroscopy methods have been used to complete the resonance assignments and determine the solution structure of the N-terminal receiver domain of the NTRC protein. Comparison of the solution structure of the NTRC receiver domain with the crystal structures of the homologous protein CheY reveals a very similar fold, with the only significant difference being the position of helix 4 relative to the rest of the protein. The determination of the structure of the NTRC receiver domain is the first step toward understanding a mechanism of signal transduction which is common to many bacterial regulatory systems.

  17. Optimizing nanodiscs and bicelles for solution NMR studies of two β-barrel membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Kucharska, Iga [University of Virginia, Center for Membrane Biology and Department of Molecular Physiology and Biological Physics (United States); Edrington, Thomas C. [Monsanto Company (United States); Liang, Binyong; Tamm, Lukas K., E-mail: Lkt2e@virginia.edu [University of Virginia, Center for Membrane Biology and Department of Molecular Physiology and Biological Physics (United States)

    2015-04-15

    Solution NMR spectroscopy has become a robust method to determine structures and explore the dynamics of integral membrane proteins. The vast majority of previous studies on membrane proteins by solution NMR have been conducted in lipid micelles. Contrary to the lipids that form a lipid bilayer in biological membranes, micellar lipids typically contain only a single hydrocarbon chain or two chains that are too short to form a bilayer. Therefore, there is a need to explore alternative more bilayer-like media to mimic the natural environment of membrane proteins. Lipid bicelles and lipid nanodiscs have emerged as two alternative membrane mimetics that are compatible with solution NMR spectroscopy. Here, we have conducted a comprehensive comparison of the physical and spectroscopic behavior of two outer membrane proteins from Pseudomonas aeruginosa, OprG and OprH, in lipid micelles, bicelles, and nanodiscs of five different sizes. Bicelles stabilized with a fraction of negatively charged lipids yielded spectra of almost comparable quality as in the best micellar solutions and the secondary structures were found to be almost indistinguishable in the two environments. Of the five nanodiscs tested, nanodiscs assembled from MSP1D1ΔH5 performed the best with both proteins in terms of sample stability and spectral resolution. Even in these optimal nanodiscs some broad signals from the membrane embedded barrel were severely overlapped with sharp signals from the flexible loops making their assignments difficult. A mutant OprH that had two of the flexible loops truncated yielded very promising spectra for further structural and dynamical analysis in MSP1D1ΔH5 nanodiscs.

  18. MAS NMR of HIV-1 protein assemblies

    Science.gov (United States)

    Suiter, Christopher L.; Quinn, Caitlin M.; Lu, Manman; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana

    2015-04-01

    The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates.

  19. UV-visible-DAD and 1H-NMR spectroscopy data fusion for studying the photodegradation process of azo-dyes using MCR-ALS.

    Science.gov (United States)

    Fernández, Cristina; Pilar Callao, M; Larrechi, M Soledad

    2013-12-15

    The photodegradation process of three azo-dyes - Acid Orange 61, Acid Red 97 and Acid Brown 425 - was monitored simultaneously by ultraviolet-visible spectroscopy with diode array detector (UV-vis-DAD) and (1)H-nuclear magnetic resonance ((1)H-NMR). Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to obtain the concentration and spectral profile of the chemical compounds involved in the process. The analysis of the H-NMR data suggests there are more intermediate compounds than those obtained with the UV-vis-DAD data. The fusion of UV-vis-DAD and the (1)H-NMR signal before the multivariate analysis provides better results than when only one of the two detector signals was used. It was concluded that three degradation products were present in the medium when the three azo-dyes had practically degraded. This study is the first application of UV-vis-DAD and (1)H-NMR spectroscopy data fusion in this field and illustrates its potential as a quick method for evaluating the evolution of the azo-dye photodegradation process. © 2013 Elsevier B.V. All rights reserved.

  20. The gel-forming behaviour of dextran in the presence of KCl: a quantitative 13C and pulsed field gradient (PFG) NMR study.

    Science.gov (United States)

    Naji, L; Schiller, J; Kaufmann, J; Stallmach, F; Kärger, J; Arnold, K

    2003-05-01

    Although the gel forming ability of certain polysaccharides in the presence of ions is a well-known phenomenon, detailed physicochemical mechanisms of such processes are still unknown. In this investigation high resolution 13C NMR as well as 1H pulsed field gradient (PFG) NMR were used to investigate the mobility of dextran in the sol and in the gel state. Gel-formation of dextran can be easily induced by the addition of large amounts of potassium chloride. No major differences in the T(1) relaxation times of dextran in the sol and in the gel state could be observed. Accordingly, the analysis of the 13C NMR spectroscopic data did not provide any indication of an observable line-broadening upon gel-formation. However, a KCl concentration dependent decrease of signal intensity in comparison to an internal standard was detected. On the other hand, the PFG NMR studies clearly indicated a gradual diminution of the self-diffusion coefficient of the dextran with increasing molecular weight as well as in the presence of potassium chloride. These measurements revealed in agreement with spectroscopic data that at least one potassium ion per monomer subunit (i.e. one glycopyranose residue) is necessary for gel formation.

  1. Acceleration of protein backbone NMR assignment by combinatorial labeling: Application to a small molecule binding study.

    Science.gov (United States)

    Hein, Christopher; Löhr, Frank; Schwarz, Daniel; Dötsch, Volker

    2017-05-01

    Selective labeling with stable isotopes has long been recognized as a valuable tool in protein NMR to alleviate signal overlap and sensitivity limitations. In this study, combinatorial (15) N-, (13) C(α) -, and (13) C'-selective labeling has been used during the backbone assignment of human cyclophilin D to explore binding of an inhibitor molecule. Using a cell-free expression system, a scheme that involves (15) N, 1-(13) C, 2-(13) C, fully (15) N/(13) C, and unlabeled amino acids was optimized to gain a maximum of assignment information from three samples. This scheme was combined with time-shared triple-resonance NMR experiments, which allows a fast and efficient backbone assignment by giving the unambiguous assignment of unique amino acid pairs in the protein, the identity of ambiguous pairs and information about all 19 non-proline amino acid types. It is therefore well suited for binding studies where de novo assignments of amide (1) H and (15) N resonances need to be obtained, even in cases where sensitivity is the limiting factor. © 2016 Wiley Periodicals, Inc.

  2. Ionic Liquid-Solute Interactions Studied by 2D NOE NMR Spectroscopy.

    Science.gov (United States)

    Khatun, Sufia; Castner, Edward W

    2015-07-23

    Intermolecular interactions between a Ru(2+)(bpy)3 solute and the anions and cations of four different ionic liquids (ILs) are investigated by 2D NMR nuclear Overhauser effect (NOE) techniques, including {(1)H-(19)F} HOESY and {(1)H-(1)H} ROESY. Four ILs are studied, each having the same bis(trifluoromethylsulfonyl)amide anion in common. Two of the ILs have aliphatic 1-alkyl-1-methylpyrrolidinium cations, while the other two ILs have aromatic 1-alkyl-3-methylimidazolium cations. ILs with both shorter (butyl) and longer (octyl or decyl) cationic alkyl substituents are studied. NOE NMR results suggest that the local environment of IL anions and cations near the Ru(2+)(bpy)3 solute is rather different from the bulk IL structure. The solute-anion and solute-cation interactions are significantly different both for ILs with short vs long alkyl tails and for ILs with aliphatic vs aromatic cation polar head groups. In particular, the solute-anion interactions are observed to be about 3 times stronger for the cations with shorter alkyl tails relative to the ILs with longer alkyl tails. The Ru(2+)(bpy)3 solute interacts with both the polar head and the nonpolar tail groups of the 1-butyl-1-methylpyrrolidinium cation but only with the nonpolar tail groups of the 1-decyl-1-methylpyrrolidinium cation.

  3. Molecular docking and NMR binding studies to identify novel inhibitors of human phosphomevalonate kinase

    Energy Technology Data Exchange (ETDEWEB)

    Boonsri, Pornthip [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States); Department of Chemistry, NANOTEC Center of Nanotechnology, National Nanotechnology Center, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Neumann, Terrence S.; Olson, Andrew L.; Cai, Sheng [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States); Herdendorf, Timothy J.; Miziorko, Henry M. [Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Hannongbua, Supa [Department of Chemistry, NANOTEC Center of Nanotechnology, National Nanotechnology Center, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Sem, Daniel S., E-mail: daniel.sem@cuw.edu [Chemical Proteomics Facility at Marquette, Department of Chemistry, Marquette University, Milwaukee, WI 53201 (United States)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Natural and synthetic inhibitors of human phosphomevalonate kinase identified. Black-Right-Pointing-Pointer Virtual screening yielded a hit rate of 15%, with inhibitor K{sub d}'s of 10-60 {mu}M. Black-Right-Pointing-Pointer NMR studies indicate significant protein conformational changes upon binding. -- Abstract: Phosphomevalonate kinase (PMK) phosphorylates mevalonate-5-phosphate (M5P) in the mevalonate pathway, which is the sole source of isoprenoids and steroids in humans. We have identified new PMK inhibitors with virtual screening, using autodock. Promising hits were verified and their affinity measured using NMR-based {sup 1}H-{sup 15}N heteronuclear single quantum coherence (HSQC) chemical shift perturbation and fluorescence titrations. Chemical shift changes were monitored, plotted, and fitted to obtain dissociation constants (K{sub d}). Tight binding compounds with K{sub d}'s ranging from 6-60 {mu}M were identified. These compounds tended to have significant polarity and negative charge, similar to the natural substrates (M5P and ATP). HSQC cross peak changes suggest that binding induces a global conformational change, such as domain closure. Compounds identified in this study serve as chemical genetic probes of human PMK, to explore pharmacology of the mevalonate pathway, as well as starting points for further drug development.

  4. Membrane lipids protected from oxidation by red wine tannins: a proton NMR study.

    Science.gov (United States)

    Furlan, Aurélien L; Jobin, Marie-Lise; Buchoux, Sébastien; Grélard, Axelle; Dufourc, Erick J; Géan, Julie

    2014-12-01

    Dietary polyphenols widespread in vegetables and beverages like red wine and tea have been reported to possess antioxidant properties that could have positive effects on human health. In this study, we propose a new in situ and non-invasive method based on proton liquid-state nuclear magnetic resonance (NMR) to determine the antioxidant efficiency of red wine tannins on a twice-unsaturated phospholipid, 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLiPC), embedded in a membrane model. Four tannins were studied: (+)-catechin (C), (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG). The lipid degradation kinetics was determined by measuring the loss of the bis-allylic protons during oxidation induced by a radical initiator, 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH). The antioxidant efficiency, i.e. the ability of tannins to slow down the lipid oxidation rate, was shown to be higher for galloylated tannins, ECG and EGCG. Furthermore, the mixture of four tannins was more efficient than the most effective tannin, EGCG, demonstrating a synergistic effect. To better understand the antioxidant action mechanism of polyphenols on lipid membranes, the tannin location was investigated by NMR and molecular dynamics. A correlation between antioxidant action of tannins and their location at the membrane interface (inserted at the glycerol backbone level) could thus be established. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Structural, vibrational, NMR, quantum chemical, DNA binding and protein docking studies of two flexible imine oximes

    Indian Academy of Sciences (India)

    YUNUS KAYA

    2016-09-01

    Two flexible imine oxime molecules, namely, 3-(pyridin-2-ylmethylimino)-butan-2-one oxime (HL¹) and 3-(pyridin-2-ylmethylimino)-pentan-2-one oxime (HL²) have been synthesized and characterized by elemental analysis, IR and NMR techniques. The conformational behavior was investigated using the density functional theory (DFT) with the B3LYP method combined with the 6-311++G(d,p) basis set. As a result of the conformational studies, three stable molecules and the most stable conformer were determined for the both imine oximes. The spectroscopic properties such as vibrational and NMR were calculated for the most stable conformer of the HL¹ and HL². The calculation results were applied to simulate infrared spectra of the title compounds, which show good agreement with observed spectra. In addition, the stable three molecules of the both imine oximes have been used to carry out DNA binding and protein docking studies with DNA and protein structures (downloaded from Protein Data Bank) using Discovery Studio 3.5 to find the most preferred binding mode of the ligands inside the DNA and protein cavity.

  6. Postharvest ripening study of sweet lime (Citrus limettioides) in situ by volume-localized NMR spectroscopy.

    Science.gov (United States)

    Banerjee, Abhishek; George, Christy; Bharathwaj, Sathyamoorthy; Chandrakumar, Narayanan

    2009-02-25

    Spatially resolved NMR--especially volume-localized spectroscopy (VLS)is useful in various fields including clinical diagnosis, process monitoring, etc. VLS carries high significance because of its ability to identify molecular species and hence track molecular events. This paper reports the application of VLS at 200 MHz to study the postharvest ripening of sweet lime ( Citrus limettioides ) in situ, including a comparative study of normal and acetylene-mediated ripening. Localization to a cubic voxel of 64 microL was achieved with point-resolved spectroscopy (PRESS). Glucose, sucrose, fructose, and citric acid are found to be among the main constituents in the fruit. In the natural process, the sugar to acid ratio increases with ripening. Ethanol generation is seen to occur at a faster rate in acetylene-mediated ripening. Whereas NMR imaging experiments including parametric imaging (e.g., T(1) or T(2) maps) may be employed for "macro" monitoring of processes such as these, this work demonstrates that the molecular imprint of the process may be tracked noninvasively by VLS.

  7. Compositional and surface characterization of HULIS by UV-Vis, FTIR, NMR and XPS: Wintertime study in Northern India

    Science.gov (United States)

    Kumar, Varun; Goel, Anubha; Rajput, Prashant

    2017-09-01

    This study (first attempt) characterizes HULIS (Humic Like Substances) in wintertime aerosols (n = 12 during day and nighttime each) from Indo-Gangetic Plain (IGP, at Kanpur) by using various state-of-the art techniques such as UV-VIS, FTIR, 1H NMR and XPS. Based on UV-Vis analysis the absorption coefficient at 365 nm (babs-365) of HULIS was found to average at 13.6 and 28.8 Mm-1 during day and nighttime, respectively. Relatively high babs-365 of HULIS during the nighttime is attributed to influence of fog-processing. However, the power fit of UV-Vis spectrum provided near similar AAE (absorption Angstrom exponent) value of HULIS centering at 4.9 ± 1.4 and 5.1 ± 1.3 during daytime and nighttime, respectively. FTIR spectra and its double derivative revealed the presence of various functional groups viz. alcohols, ketones aldehydes, carboxylic acids as well as unsaturated and saturated carbon bonds. 1H NMR spectroscopy was applied to quantify relative percentage of various types of hydrogen atoms contained in HULIS, whereas XPS technique provided information on surface composition and oxidation states of various elements present. A significantly high abundance of H‒C‒O group has been observed in HULIS (based on 1H NMR); 41.4± 2.7% and 30.9± 2.4% in day and nighttime, respectively. However, aromatic protons (Ar-H) were higher in nighttime samples (19.3± 1.8%) as compared to that in daytime samples (7.5 ± 1.9). XPS studies revealed presence of various species on the surface of HULIS samples. Carbon existed in 7 different chemical states while total nitrogen and sulfur exhibited 3 and 2 different oxidation states (respectively) on the surface of HULIS. This study reports structural information and absorption properties of HULIS which has implications to their role as cloud condensation nuclei and atmospheric direct radiative forcing.

  8. Advances in studying order and dynamics in condensed matter by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Voda, M.A.

    2006-07-13

    In this thesis, molecular transport in liquid samples is studied in terms of susceptibility induced magnetic field inhomogeneities and spectral distortions for interdiffusion in binary mixtures. Molecular order and dynamics are topics for two different soft solids, natural rubber and polyurethane. The influence of the mixture heterogeneity on the magnetic field homogeneity was investigated in terms of a spatial and time-dependent magnetic susceptibility. The effect of the heterogeneous distribution of magnetic susceptibility in liquid mixtures on the static and rf field homogeneity was simulated together with the corresponding spectral distortions. The problem of low magnetic field homogeneity provided by the Halbach type of magnets is discussed. The design of modified Halbach magnets is studied in order to increase the field homogeneity. The work was focused on two types of Halbach magnets, consisting of 16 and 24 magnet blocks, respectively. Different modifications were applied to these magnet designs, and the field homogeneity was significantly improved. The changes induced in molecular dynamics and order in stretched elastomers was investigated using multispin moments edited by multiple-quantum NMR. The main purpose of this part is to investigate the changes in proton residual dipolar coupling and the sensitivity of multiple quantum coherences of higher order for cross-linked natural rubber under uniaxial deformation. The effect of uniaxial deformation of a natural rubber band was investigated by measurements of second van Vleck moments and fourth moments edited by double-quantum and triple-quantum coherences, respectively. A spin diffusion experiment was employed for the elucidation of the morphology and domain sizes of a series of polyurethane samples. A proton DQ dipolar filer was used to select the magnetization of the rigid phase. The most probable morphology is three-dimensional for the TPU samples with a high content in HS as was established by a

  9. Membrane protein-lipid interactions in mixed micelles studied by NMR spectroscopy with the use of paramagnetic reagents.

    Science.gov (United States)

    Hilty, Christian; Wider, Gerhard; Fernández, César; Wüthrich, Kurt

    2004-04-02

    For solution NMR studies of the structure and function of membrane proteins, these macromolecules have to be reconstituted and solubilized in detergent micelles. Detailed characterization of the mixed detergent/protein micelles is then of key importance to validate the results from such studies, and to evaluate how faithfully the natural environment of the protein in the biological membrane is mimicked by the micelle. In this paper, a selection of paramagnetic probes with different physicochemical properties are used to characterize the 60 kDa mixed micelles consisting of about 90 molecules of the detergent dihexanoylphosphatidylcholine (DHPC) and one molecule of the Escherichia coli outer-membrane protein X (OmpX), which had previously been extensively studied by solution NMR techniques. The observation of highly selective relaxation effects on the NMR spectra of OmpX and DHPC from a water-soluble relaxation agent and from nitroxide spin labels attached to lipophilic molecules, confirmed data obtained previously with more complex NMR studies of the diamagnetic OmpX/DHPC system, and yielded additional novel insights into the protein-detergent interactions in the mixed micelles. The application of paramagnetic probes to the well-characterized OmpX/DHPC system indicates that such probes should be widely applicable as an efficient support of NMR studies of the topology of mixed membrane protein-detergent micelles.

  10. Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae—A 2D NMR Metabolomics Study

    Science.gov (United States)

    Vergara, Fredd; Shino, Amiu; Kikuchi, Jun

    2016-01-01

    Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea). Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal), the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR) and principal component analysis (PCA). Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of 1H-13C HSQC (Heteronuclear Single Quantum Coherence) signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae. PMID:27598144

  11. Binding and NMR structural studies on indoloquinoline-oligonucleotide conjugates targeting duplex DNA.

    Science.gov (United States)

    Eick, Andrea; Riechert-Krause, Fanny; Weisz, Klaus

    2012-06-20

    An 11-phenyl-indolo[3,2-b]quinoline (PIQ) was tethered through an aminoalkyl linker to the 5'-end of four pyrimidine oligonucleotides with T/C scrambled sequences at their two 5'-terminal positions. Binding to different double-helical DNA targets formed parallel triple helices with a PIQ-mediated stabilization that strongly depends on pH and the terminal base triad at the 5'-triplex-duplex junction. The most effective stabilization was observed with a TAT triplet at the 5'-junction under low pH conditions, pointing to a protonated ligand with a high triplex binding affinity and unfavorable charge repulsions in the case of a terminal C(+)GC triplet at the junction. The latter preference of the PIQ ligand for TAT over CGC is alleviated yet still preserved at higher pH. Intercalation of PIQ at the 5'-triplex-duplex junction as suggested by the triplex melting experiments was confirmed by homonuclear and heteronuclear NMR structural studies on a specifically isotope-labeled triplex. The NMR analysis revealed two coexisting species that only differ by a 180° rotation of the indoloquinoline within the intercalation pocket. NOE-derived molecular models indicate extensive stacking interactions of the indoloquinoline moiety with the TAT base triplet and CG base pair at the junction and a phenyl substituent that is positioned in the major groove and oriented almost perpendicular to the plane of the indoloquinoline.

  12. Biochemical effects of gadolinium chloride in rats liver and kidney studied by 1H NMR metabolomics

    Institute of Scientific and Technical Information of China (English)

    LIAO Peiqiu; WEI Lai; Wu Huifeng; LI Weisheng; WU Yijie; LI Xiaojing; NI Jiazuan; PEI Fengkui

    2009-01-01

    The biochemical effects of gadolinium chloride were studied using high-resolution IH nuclear magnetic resonance (NMR) spec-troscopy to investigate the biochemical composition of tissue (liver and kidney) aqueous extracts obtained from control and gadolinium chlo-ride (GdCl3) (10 and 50 mg/kg body weight, intraperitoneal injection, i.p.) treated rats. Tissue samples were collected at 48, 96 and 168 h p.d. after exposure to GdCl3, and extracted using methanol/chloroform solvent system. 1H NMR spectra of tissue extracts were analyzed by pat-tern recognition using principal components analysis. The liver damages caused by GdCl3 were characterized by increased succinate and de-creased glycogen level and elevated lactate, alanine and betaine concentration in liver. Furthermore, the increase of creatine and lactate, and decrease of glutamate, alanine, phosphocholine, glycophosphocholine (GPC), betaine, myo-inositoi and trimethylamine N-oxide (TMAO)levels in kidney illustrated kidney disturbance induced by GdCl3.

  13. Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae—A 2D NMR Metabolomics Study

    Directory of Open Access Journals (Sweden)

    Fredd Vergara

    2016-09-01

    Full Text Available Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea. Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal, the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR and principal component analysis (PCA. Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of 1H-13C HSQC (Heteronuclear Single Quantum Coherence signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae.

  14. Lanthanide Chelates as Bilayer Alignment Tools in NMR Studies of Membrane-Associated Peptides

    Science.gov (United States)

    Prosser, R. S.; Bryant, H.; Bryant, R. G.; Vold, Regitze R.

    1999-12-01

    Theequimolar complex, consisting of the lipid-like, amphiphilic chelating agent 1,11-bis[distearylamino]-diethylenetriamine pentaacetic acid (DTPA-18) and Tm3+, is shown by deuterium (2H) NMR to be useful in aligning bicelle-like model membranes, consisting of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC). As shown previously (1996, R. S. Prosser et al., J. Am. Chem. Soc. 118, 269-270), in the absence of chelate, the lanthanide ions bind loosely with the lipid phosphate groups and confer the membrane with a sufficient positive magnetic anisotropy to result in parallel alignment (i.e., average bilayer normal along the field). Apparently, DTPA-18 sequesters the lanthanide ions and inserts into the phospholipid bilayer in such a manner that bilayer morphology is preserved over a wide temperature range (35-70°C). The inherent paramagnetic shifts and line broadening effects are illustrated by 2H NMR spectra of the membrane binding peptide, Leu-enkephalin (Lenk-d2, Tyr-(Gly-d2)-Gly-Phe-Leu-OH), in the presence of varying concentrations of Tm3+, and upon addition of DTPA-18. Two conclusions could be drawn from this study: (1) The addition of Tm3+ to the bicelle system is consistent with a conformational change in the surface associated peptide, and this effect is shown to be reversed by addition of the chelate, and (2) The paramagnetic shifts are shown to be significantly reduced by addition of chelate.

  15. Morphological Characterization of DMPC/CHAPSO Bicellar Mixtures: A Combined SANS and NMR Study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming [University of Connecticut, Storrs; Morales, Hannah H [University of Toronto, Canada; Katsaras, John [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Yang, Yongkun [University of Connecticut, Storrs; Macdonald, P [University of Toronto, Canada; Nieh, Mu-Ping [University of Connecticut, Storrs

    2013-01-01

    Spontaneously forming structures of a system composed of dimyristoyl phosphatidylcholine (DMPC) and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) were studied by small-angle neutron scattering (SANS), 31P NMR, and stimulated echo (STE) pulsed field gradient (PFG) 1H NMR diffusion measurements. Charged lipid dimyristoyl phosphatidylglycerol (DMPG) was used to induce different surface charge densities. The structures adopted were investigated as a function of temperature and lipid concentration for samples with a constant molar ratio of long-chain to short-chain lipids (=3). In the absence of DMPG, zwitterionic bicellar mixtures exhibited a phase transition from discoidal bicelles, or ribbons, to multilamellar vesicles either upon dilution or with increased temperature. CHAPSO-containing mixtures showed a higher thermal stability in morphology than DHPC-containing mixtures at the corresponding lipid concentrations. In the presence of DMPG, discoidal bicelles (or ribbons) were also found at low temperature and lower lipid concentration mixtures. At high temperature, perforated lamellae were observed in high concentration mixtures ( 7.5 wt %) whereas uniform unilamellar vesicles and bicelles formed in low-concentration mixtures ( 2.5 wt %), respectively, when the mixtures were moderately and highly charged. From the results, spontaneous structural diagrams of the zwitterionic and charged systems were constructed.

  16. PdGa intermetallic hydrogenation catalyst: an NMR and physical property study.

    Science.gov (United States)

    Klanjšek, M; Gradišek, A; Kocjan, A; Bobnar, M; Jeglič, P; Wencka, M; Jagličić, Z; Popčević, P; Ivkov, J; Smontara, A; Gille, P; Armbrüster, M; Grin, Yu; Dolinšek, J

    2012-02-29

    The PdGa intermetallic compound is a highly selective and stable heterogeneous hydrogenation catalyst for the semi-hydrogenation of acetylene. We have studied single crystals of PdGa grown by the Czochralski technique. The (69)Ga electric-field-gradient (EFG) tensor was determined by means of NMR spectroscopy, giving experimental confirmation of both the recently refined structural model of PdGa and the theoretically predicted Pd-Ga covalent bonding scheme. The hydrogenation experiment has detected no hydrogen uptake in the PdGa, thus preventing in situ hydride formation that leads to a reduction of the catalytic selectivity. We have also determined bulk physical properties (the magnetic susceptibility, the electrical resistivity, the thermoelectric power, the Hall coefficient, the thermal conductivity and the specific heat) of single-crystalline PdGa. The results show that PdGa is a diamagnet with metallic electrical resistivity and moderately high thermal conductivity. The thermoelectric power is negative with complicated temperature dependence, whereas the Hall coefficient is positive and temperature-dependent, indicating complexity of the Fermi surface. Partial fulfillment of the NMR Korringa relation reveals that the charge carriers are weakly correlated. Specific heat measurements show that the density of electronic states (DOS) at the Fermi energy of PdGa is reduced to 15% of the DOS of the elemental Pd metal.

  17. Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae-A 2D NMR Metabolomics Study.

    Science.gov (United States)

    Vergara, Fredd; Shino, Amiu; Kikuchi, Jun

    2016-09-02

    Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea). Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal), the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR) and principal component analysis (PCA). Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of ¹H-(13)C HSQC (Heteronuclear Single Quantum Coherence) signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae.

  18. Theoretical study of NMR, infrared and Raman spectra on triple-decker phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga, 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic properties of multi-decker phthalocyanines were studied by theoretical calculation. Electronic structures, excited processes at multi-states, isotropic chemical shifts of {sup 13}C, {sup 14}N and {sup 1}H-nuclear magnetic resonance (NMR), principle V-tensor in electronic field gradient (EFG) tensor and asymmetry parameters (η), vibration mode in infrared (IR) and Raman spectra of triple-decker phthalocyanines were calculated by density functional theory (DFT) and time-dependent DFT using B3LYP as basis function. Electron density distribution was delocalized on the phthalocyanine rings with electron static potential. Considerable separation of chemical shifts in {sup 13}C, {sup 14}N and {sup 1}H-NMR was originated from nuclear spin interaction between nitrogen and carbon atoms, nuclear quadrupole interaction based on EFG and η of central metal under crystal field. Calculated optical absorption at multi-excited process was derived from overlapping π-orbital on the phthalocyanine rings. The vibration modes in IR and Raman spectra were based on in-plane deformation and stretching vibrations of metal-ligand coordination bond on the deformed structure.

  19. Evidence of vintage effects on grape wines using 1H NMR-based metabolomic study.

    Science.gov (United States)

    Lee, Jang-Eun; Hwang, Geum-Sook; Van Den Berg, Frans; Lee, Cherl-Ho; Hong, Young-Shick

    2009-08-19

    The chemical composition of grape wines varies with grape variety, environmental factors of climate and soil, and bacterial strains, which can each affect the wine quality. Using (1)H NMR analysis coupled with multivariate statistical data sets, we investigated the effects of grape vintage on metabolic profiles of wine and the relationship between wine metabolites and meteorological data. Principal component analysis (PCA) showed a clear differentiation between Meoru wines that were vinified with the same yeast strain and Meoru grapes harvested from the same vineyard but with a different vintage. The metabolites contributing to the differentiation were identified as 2,3-butandiol, lactic acid, alanine, proline, gamma-aminobutyric acid (GABA), choline, and polyphenols, by complementary PCA loading plot. Markedly higher levels of proline, lactic acid and polyphenols were observed in the 2006 vintage wines compared to those of 2007 vintage, showing excellent agreement with the meteorological data that the sun-exposed time and rainfall in 2006 were approximately two times more and four times less, respectively, than those in 2007. These results revealed the important role of climate during ripening period in the chemical compositions of the grape. This study highlights the reliability of NMR-based metabolomic data by integration with meteorological data in characterizing wine or grape.

  20. High-resolution /sup 27/Al NMR study of calcium aluminate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yakerson, V.I.; Nissenbaum, V.D.; Golosman, E.Z.; Mastikhin, V.M.

    1987-06-01

    The high-resolution /sup 27/Al NMR spectra of calcium aluminates, calcium hydroaluminates, and calcium alumina supports and catalysts have been studied. The structures of the anhydrous calcium aluminates (CaAl/sub 2/O/sub 3/, CaAl/sub 4/O/sub 7/, 3CaO x Al/sub 2/O/sub 3/, 12CaO x 7Al/sub 2/O/sub 3/, talyum) consist of aluminum-oxygen tetrahedra and contain various types of aluminum atoms, the nonequivalence of which increases in going from strongly basic to weakly basic aluminates. In the NMR spectrum the signal of octahedrally coordinated aluminum is due to disordered aluminum-oxygen structures. During the forming of the calcium-alumina catalysts and supports the process (AlO/sub 4/) ..-->.. (AlO/sub 6/) takes place during hydration, and (AlO/sub 6/) ..-->.. (AlO/sub 4/) during thermolysis; the nonequivalence of the tetrahedrally coordinated aluminum atoms decreases, while the (AlO/sub 4/):(AlO/sub 6/) ratio decreases as the degree of hydration increases.

  1. Studies on solution NMR structure of brazzein——Secondary structure and molecular scaffold

    Institute of Scientific and Technical Information of China (English)

    高广华; 戴继勋; 丁鸣; 王金凤; 王大成

    1999-01-01

    Brazzein is a sweet-tasting protein isolated from the fruit of West African plant Pentadiplandra brazzeana Baillon. It is the smallest and the most water-soluble sweet protein discovered so far and is highly thermostable. The proton NMR study of brazzein at 600 MHz (pH 3.5, 300 K) is presented. The complete sequence specific assignments of the individual backbone and sideehain proton resonances were achieved using through-bond and through-space eonneetivities obtained from standard two-dimensional NMR techniques. The secondary structure of brazzein contains one α-helix (residues 21—29), one short 310-helix (residues 14—17), two strands of antiparallel β-sheet (residues 34—39, 44—50) and probably a third strand (residues 5—7) near the N-terminus. A comparative analysis found that brazzein shares a so-called ’eysteine-stabilized alpha-beta’ (CSαβ) motif with scorpion neurotoxins, insect defensins and plant γ-thionins. The significance of this multi-function motif, the possible active sites an

  2. Active site dynamics in NADH oxidase from Thermus thermophilus studied by NMR spin relaxation.

    Science.gov (United States)

    Miletti, Teresa; Farber, Patrick J; Mittermaier, Anthony

    2011-09-01

    We have characterized the backbone dynamics of NADH oxidase from Thermus thermophilus (NOX) using a recently-developed suite of NMR experiments designed to isolate exchange broadening, together with (15)N R (1), R (1ρ ), and {(1)H}-(15)N steady-state NOE relaxation measurements performed at 11.7 and 18.8 T. NOX is a 54 kDa homodimeric enzyme that belongs to a family of structurally homologous flavin reductases and nitroreductases with many potential biotechnology applications. Prior studies have suggested that flexibility is involved in the catalytic mechanism of the enzyme. The active site residue W47 was previously identified as being particularly important, as its level of solvent exposure correlates with enzyme activity, and it was observed to undergo "gating" motions in computer simulations. The NMR data are consistent with these findings. Signals from W47 are dynamically broadened beyond detection and several other residues in the active site have significant R ( ex ) contributions to transverse relaxation rates. In addition, the backbone of S193, whose side chain hydroxyl proton hydrogen bonds directly with the FMN cofactor, exhibits extensive mobility on the ns-ps timescale. We hypothesize that these motions may facilitate structural rearrangements of the active site that allow NOX to accept both FMN and FAD as cofactors.

  3. Improved Efficiency of Molecular-Gel Formation by Adjusting Preorganization of Amino-Acid-Derived Flexible Molecules: A NMR and Thermodynamic study.

    Science.gov (United States)

    Angulo-Pachón, César A; Gascó-Catalán, Carolina; Ojeda-Flores, Juan J; Miravet, Juan F

    2016-07-04

    The efficiency of the formation of molecular gels of simple derivatives of l-valine and l-isoleucine is greatly improved in different organic solvents when a hexyl fragment is replaced by a bulkier cyclohexyl one. A study using NMR and IR spectroscopy provides information on the preferred conformations of the molecules, indicating that the cyclohexyl moiety precludes intramolecular H bonding and preorganises the system for intermolecular interactions, which are responsible for fiber formation. NMR data of the gels provides thermodynamic data on fibrillization, revealing that the origin of this effect is mainly entropic. Electron microscopy (SEM and TEM) images show fibrillar and tape-like objects, which are observed commonly in molecular gels. Rheological measurements reveal significant differences between cyclohexyl and hexyl appended gelators. These findings could contribute to the rational design of small, flexible, building blocks for self-assembly.

  4. An NMR Study on Cinerin II%瓜菊酯II的NMR数据解析

    Institute of Scientific and Technical Information of China (English)

    张海艳; 范毅; 赵天增

    2015-01-01

    从除虫菊酯中分离得到瓜菊酯II,通过DEPT及1H-1HCOSY,HSQC,HMBC,NOESY等2D NMR技术对该化合物所有的1H和13C NMR信号进行了详细解析和全归属。%Cinerin II was isolated from pyrethrins. The 1H and 13C NMR chemical shifts of the compounds were completely assigned by using a combination of 1D NMR(1H,13C NMR and DEPT)and 2D NMR(1H-1H COSY, HSQC,HMBC and NOESY)techniques.

  5. Studies of metal-biomolecule systems in liquids with beta-detected NMR

    CERN Document Server

    Walczak, Michal

    2017-01-01

    My internship took place within a small research team funded via the European Research Council (ERC Starting Grant: Beta-Drop NMR) at ISOLDE. It was devoted to laser spin-polarization and beta-detected NMR techniques and their future applications in chemistry and biology. I was involved in the design and tests of the beta-NMR spectrometer which will be used in the upcoming experiments. In this way I have been exposed to many topics in physics (atomic and nuclear physics), experimental techniques (vacuum technology, lasers, beta detectors, electronics, DAQ software), as well as chemistry and biology (NMR on metal ions, metal ion binding to biomolecules, quantum chemistry calculations).

  6. Sepsis does not alter red blood cell glucose metabolism or Na+ concentration: A 2H-, 23Na-NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Hotchkiss, R.S.; Song, S.K.; Ling, C.S.; Ackerman, J.J.; Karl, I.E. (Washington Univ. School of Medicine, St. Louis (USA))

    1990-01-01

    The effects of sepsis on intracellular Na+ concentration ((Na+)i) and glucose metabolism were examined in rat red blood cells (RBCs) by using 23Na- and 2H-nuclear magnetic resonance (NMR) spectroscopy. Sepsis was induced in 15 halothane-anesthetized female Sprague-Dawley rats by using the cecal ligation and perforation technique; 14 control rats underwent cecal manipulation without ligation. The animals were fasted for 36 h, but allowed free access to water. At 36 h postsurgery, RBCs were examined by 23Na-NMR by using dysprosium tripolyphosphate as a chemical shift reagent. Human RBCs from 17 critically ill nonseptic patients and from 7 patients who were diagnosed as septic were also examined for (Na+)i. Five rat RBC specimens had (Na+)i determined by both 23Na-NMR and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). For glucose metabolism studies, RBCs from septic and control rats were suspended in modified Krebs-Henseleit buffer containing (6,6-2H2)glucose and examined by 2H-NMR. No significant differences in (Na+)i or glucose utilization were found in RBCs from control or septic rats. There were no differences in (Na+)i in the two groups of patients. The (Na+)i determined by NMR spectroscopy agreed closely with measurements using ICP-AES and establish that 100% of the (Na+)i of the RBC is visible by NMR. Glucose measurements determined by 2H-NMR correlated closely (correlation coefficient = 0.93) with enzymatic analysis. These studies showed no evidence that sepsis disturbed RBC membrane function or metabolism.

  7. Solid-state NMR/NQR and first-principles study of two niobium halide cluster compounds.

    Science.gov (United States)

    Perić, Berislav; Gautier, Régis; Pickard, Chris J; Bosiočić, Marko; Grbić, Mihael S; Požek, Miroslav

    2014-01-01

    Two hexanuclear niobium halide cluster compounds with a [Nb6X12](2+) (X=Cl, Br) diamagnetic cluster core, have been studied by a combination of experimental solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were determined by using variable Bo field static broadband NMR measurements and additional NQR measurements. It was found that they possess large positive chemical shifts, contrary to majority of niobium compounds studied so far by solid-state NMR, but in accordance with chemical shifts of (95)Mo nuclei in structurally related compounds containing [Mo6Br8](4+) cluster cores. Experimentally determined δiso((93)Nb) values are in the range from 2,400 to 3,000 ppm. A detailed analysis of geometrical relations between computed electric field gradient (EFG) and chemical shift (CS) tensors with respect to structural features of cluster units was carried out. These tensors on niobium sites are almost axially symmetric with parallel orientation of the largest EFG and the smallest CS principal axes (Vzz and δ33) coinciding with the molecular four-fold axis of the [Nb6X12](2+) unit. Bridging halogen sites are characterized by large asymmetry of EFG and CS tensors, the largest EFG principal axis (Vzz) is perpendicular to the X-Nb bonds, while intermediate EFG principal axis (Vyy) and the largest CS principal axis (δ11) are oriented in the radial direction with respect to the center of the cluster unit. For more symmetrical bromide compound the PAW predictions for EFG parameters are in better correspondence with the NMR/NQR measurements than in the less symmetrical chlorine compound. Theoretically predicted NMR parameters of bridging halogen sites were checked by (79/81)Br NQR and (35)Cl solid-state NMR measurements.

  8. A STD-NMR Study of the Interaction of the Anabaena Ferredoxin-NADP+ Reductase with the Coenzyme

    Directory of Open Access Journals (Sweden)

    Lara V. Antonini

    2014-01-01

    Full Text Available Ferredoxin-NADP+ reductase (FNR catalyzes the electron transfer from ferredoxin to NADP+ via its flavin FAD cofactor. To get further insights in the architecture of the transient complexes produced during the hydride transfer event between the enzyme and the NADP+ coenzyme we have applied NMR spectroscopy using Saturation Transfer Difference (STD techniques to analyze the interaction between FNRox and the oxidized state of its NADP+ coenzyme. We have found that STD NMR, together with the use of selected mutations on FNR and of the non-FNR reacting coenzyme analogue NAD+, are appropriate tools to provide further information about the the interaction epitope.

  9. Integration of XAS and NMR techniques for the structure determination of metalloproteins. Examples from the study of copper transport proteins.

    Science.gov (United States)

    Banci, Lucia; Bertini, Ivano; Mangani, Stefano

    2005-01-01

    Nuclear magnetic resonance (NMR) is a powerful technique for protein structure determination in solution. However, when dealing with metalloproteins, NMR methods are unable to directly determine the structure of the metal site and its coordination geometry. The capability of X-ray absorption spectroscopy (XAS) to provide the structure of a metal ion bound to a protein is then perfectly suited to complement the process of the structure determination. This aspect is particularly relevant in structural genomic projects where high throughput of structural results is the main goal. The synergism of the two techniques has been exploited in the structure determination of bacterial copper transport proteins.

  10. NMR spectroscopic search module for Spektraris, an online resource for plant natural product identification--Taxane diterpenoids from Taxus × media cell suspension cultures as a case study.

    Science.gov (United States)

    Fischedick, Justin T; Johnson, Sean R; Ketchum, Raymond E B; Croteau, Rodney B; Lange, B Markus

    2015-05-01

    Development and testing of Spektraris-NMR, an online spectral resource, is reported for the NMR-based structural identification of plant natural products (PNPs). Spektraris-NMR allows users to search with multiple spectra at once and returns a table with a list of hits arranged according to the goodness of fit between query data and database entries. For each hit, a link to a tabulated alignment of (1)H NMR and (13)C NMR spectroscopic peaks (query versus database entry) is provided. Furthermore, full spectroscopic records and experimental meta information about each database entry can be accessed online. To test the utility of Spektraris-NMR for PNP identification, the database was populated with NMR data (total of 466 spectra) for ∼ 250 taxanes, which are structurally complex diterpenoids (including the anticancer drug taxol) commonly found in the genus Taxus. NMR data generated with metabolites purified from Taxus cell suspension cultures were then used to search Spektraris-NMR, and enabled the identification of eight taxanes with high confidence. A ninth isolated metabolite could be assigned, based on spectral searches, to a taxane skeletal class, but no high confidence hit was produced. Using various spectroscopic methods, this metabolite was characterized as 2-deacetylbaccatin IV, a novel taxane. These results indicate that Spektraris-NMR is a valuable resource for rapid and reliable identification of known metabolites and has the potential to contribute to de-replication efforts in novel PNP discovery.

  11. High-pressure low-temperature locknut cell for both EPR and NMR studies to 10 kilobars and 77 K

    Science.gov (United States)

    Sinha, Shantanu; Srinivasan, R.

    1983-11-01

    A locked high-pressure cell with working pressure range up to 10 kbars suitable for low-temperature studies to 77 K has been described. It can be used for both EPR and NMR studies of single crystals (and other solid samples). The high-pressure seal and all other aspects of the cell remain the same for either application. Only a change of the bottom plug is required for a switch from a nuclear-magnetic-resonance (NMR) to an electron-paramagnetic-resonance (EPR) experiment. Details of the procedure for the calibration of pressure inside the cell at various temperatures are discussed. The performance of the cell in EPR (Cr3+ion) and NMR (27Al nucleus) studies is reported.

  12. Molecular motions in thermotropic liquid crystals studied by NMR spin-lattice relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Zamar, R.C.; Gonzalez, C.E.; Mensio, O. [Cordoba Univ. Nacional (Argentina). Facultad de Matematica, Astronomia y Fisica

    1998-12-01

    Nuclear magnetic resonance relaxation experiments with field cycling techniques proved to be a valuable tool for studying molecular motions in liquid crystals, allowing a very broad Larmor frequency variation, sufficient to separate the cooperative motions from the liquid like molecular diffusion. In new experiments combining NMR field cycling with the Jeener-Broekaert order-transfer pulse sequence, it is possible to measure the dipolar order relaxation time (T{sub 1D}), in addition to the conventional Zeeman relaxation time (T{sub 1Z}) in a frequency range of several decades. When applying this technique to nematic thermotropic liquid crystals, T{sub 1D} showed to depend almost exclusively on the order fluctuation of the director mechanism in the whole frequency range. This unique characteristic of T{sub 1D} makes dipolar order relaxation experiments specially useful for studying the frequency and temperature dependence of the spectral properties of the collective motions. (author)

  13. 93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20

    Science.gov (United States)

    Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

    2015-03-01

    We report a study of 93Nb- and 27Al-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a praseodymium based compound PrNb2Al20. The observed NMR line at around 3 T and 30 K shows a superposition of typical powder patterns of one Nb signal and at least two Al signals. 93Nb-NMR line could be reproduced by using the previously reported NQR frequency νQ ≊ 1.8MHz and asymmetry parameter η ≊ 0 [Kubo T et al 2014 JPS Conf. Proc. 3 012031]. From 27Al-NMR/NQR, NQR parameters are obtained to be νQ,A ≊ 1.53 MHz, and ηA ≊ 0.20 for the site A, and νQ,B ≊ 2.28 MHz, and ηB ≊ 0.17 for the site B. By comparing this result with the previous 27Al-NMR study of PrT2Al20 (T = Ti, V) [Tokunaga Y et al 2013 Phys. Rev. B 88 085124], these two Al site are assigned to the two of three crystallographycally inequivalent Al sites.

  14. Binding events of (S )-N -(3-oxo-octanoyl)-homoserine lactone with agrobacterium tumefaciens mutant cells studied by saturation transfer difference NMR

    Energy Technology Data Exchange (ETDEWEB)

    Cabeca, Luis Fernando; Pomini, Armando Mateus; Cruz, Pedro Luiz R.; Marsaioli, Anita J. [University of Campinas (UNICAMP), SP (Brazil). Chemistry Inst.

    2011-07-01

    Quorum-sensing is a widely studied communication phenomenon in bacteria, which involves the production and detection of signaling substances in relation with cell density and colony behavior. Herein, the membrane binding interactions of the signal (S)-N-(3-oxo-octanoyl)-HSL with A. tumefaciens NTL4(pZLR4) cells were studied using saturation transfer difference NMR spectroscopy (STD-NMR). The substance epitope map was obtained showing that the hydrophobic acyl chain is the most important interacting site for the signal and the cell membrane. Results were interpreted upon comparisons with a simpler system, using liposomes as membrane models. Some insights on the use of b-cyclodextrin as acyl-HSL carrier were also provided. (author)

  15. NMR-based metabolite profiling of human milk: A pilot study of methods for investigating compositional changes during lactation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junfang [Department of Chemistry, Umeå University (Sweden); Domellöf, Magnus [Department of Clinical Sciences, Pediatrics, Umeå University (Sweden); Zivkovic, Angela M. [Foods for Health Institute, University of California, Davis, CA (United States); Department of Nutrition, University of California, Davis, CA (United States); Larsson, Göran [Department of Medical Biochemistry and Biophysics, Unit of Research, Education and Development-Östersund, Umeå University (Sweden); Öhman, Anders, E-mail: anders.ohman01@umu.se [Department of Pharmacology and Clinical Neuroscience, Umeå University (Sweden); Nording, Malin L., E-mail: malin.nording@umu.se [Department of Chemistry, Umeå University (Sweden)

    2016-01-15

    Low-molecular-weight metabolites in human milk are gaining increasing interest in studies of infant nutrition. In the present study, the milk metabolome from a single mother was explored at different stages of lactation. Metabolites were extracted from sample aliquots using either methanol/water (MeOH/H{sub 2}O) extraction or ultrafiltration. Nuclear magnetic resonance (NMR) spectroscopy was used for metabolite identification and quantification, and multi- and univariate statistical data analyses were used to detect changes over time of lactation. Compared to MeOH/H{sub 2}O extraction, ultrafiltration more efficiently reduced the interference from lipid and protein resonances, thereby enabling the identification and quantification of 36 metabolites. The human milk metabolomes at the early (9–24 days after delivery) and late (31–87 days after delivery) stages of lactation were distinctly different according to multi- and univariate statistics. The late lactation stage was characterized by significantly elevated concentrations of lactose, choline, alanine, glutamate, and glutamine, as well as by reduced levels of citrate, phosphocholine, glycerophosphocholine, and N-acetylglucosamine. Our results indicate that there are significant compositional changes of the human milk metabolome also in different phases of the matured lactation stage. These findings complement temporal studies on the colostrum and transitional metabolome in providing a better understanding of the nutritional variations received by an infant. - Highlights: • 36 metabolites were simultaneously quantified in human milk by NMR. • Ultrafiltration more efficiently reduces interferences than MeOH/H{sub 2}O extraction. • Compositional changes of the human milk exist during the matured lactation stage.

  16. 13C cpmas nmr and molecular modeling in the studies of new analogues of buspirone.

    Science.gov (United States)

    Pisklak, Maciej; Perliński, Mirosław; Kossakowski, Jerzy; Wawer, Iwona

    2002-01-01

    Three derivatives of 1,4 dichloro-dibenzo[e,h]-bicyclo[2.2.3]octane-2,3-dicarboximide were examined by 13C CPMAS NMR. Low energy conformations were found by a semi-empirical AM1 approach, NMR shielding constants were calculated using the GIAO RHF method.

  17. Real-time NMR studies of electrochemical double-layer capacitors.

    Science.gov (United States)

    Wang, Hao; Köster, Thomas K-J; Trease, Nicole M; Ségalini, Julie; Taberna, Pierre-Louis; Simon, Patrice; Gogotsi, Yury; Grey, Clare P

    2011-12-07

    (11)B NMR spectroscopy has been used to investigate the sorption of BF(4)(-) anions on a highly porous, high surface area carbon, and different binding sites have been identified. By implementing in situ NMR approaches, the migration of ions between the electrodes of the supercapacitors and changes in the nature of ion binding to the surface have been observed in real time.

  18. Solid state NMR and pair distribution function studies of silicon electrodes for lithium-ion batteries

    Science.gov (United States)

    Key, Baris

    The universally used negative electrode material in a LIB is carbon, because of its moderate capacity (372 mAhg-1 for graphite), cyclability and high rate capability. However, new, low cost, safe electrode materials with higher capacities are still urgently required for both portable and transportation applications. Silicon anodes are particularly attractive alternatives to carbon with extremely high gravimetric energy densities (3572 mAhg-1). Compared to graphite, silicon has a massive volumetric capacity of 8322 mAhcm-3 (calculated based on the original volume of silicon) which is approximately ten times that graphite. At room temperature, upon electrochemical lithiation, silicon undergoes a crystalline to amorphous phase transition forming a lithiated amorphous silicide phase. Unfortunately, due to the amorphous nature of the lithiated silicides, it is not possible to monitor all the structural changes that occur during lithium insertion/removal with conventional methods such as diffraction. The short range order of the amorphous materials remains unknown, preventing attempts to optimize performance based on electrochemical-structure correlations. In this work, a combination of local structure probes, ex-situ 7Li nuclear magnetic resonance (NMR) studies and pair distribution function (PDF) analysis of X-ray data was applied to investigate the changes in short range order that occur during the initial charge and discharge cycles. The distinct electrochemical profiles observed subsequent to the 1 st discharge have been shown to be associated with the formation of distinct amorphous lithiated silicide structures. A (de)lithiation model consisting of four different mechanisms, each being valid for regions of the charge or discharge process is proposed to explain the hysteresis and the steps in the electrochemical profile observed during lithiation and delithiation of Si. A spontaneous reaction of the fully lithiated lithium silicide with the electrolyte is directly

  19. Localization and interaction of hydroxyflavones with lipid bilayer model membranes: a study using DSC and multinuclear NMR.

    Science.gov (United States)

    Sinha, Ragini; Joshi, Akshada; Joshi, Urmila J; Srivastava, Sudha; Govil, Girjesh

    2014-06-10

    The localization and interaction of six naturally occurring flavones (FLV, 5HF, 6HF, 7HF, CHY and BLN) in DPPC bilayers were studied using DSC and multi-nuclear NMR. DSC results indicate that FLV and 6HF interact with alkyl chains. The (1)H NMR shows interaction of flavones with the sn-glycero region. Ring current induced chemical shifts indicate that 6HF and BLN acquire parallel orientation in bilayers. 2D NOESY spectra indicate partitioning of the B-ring into the alkyl chain region. The DSC, NMR and binding studies indicate that 5HF and 7HF are located near head group region, while 6HF, CHY and BLN are located in the vicinity of sn-glycero region, and FLV is inserted deepest in the membrane.

  20. Applications of Solid-State NMR Spectroscopy for the Study of Lipid Membranes with Polyphilic Guest (MacroMolecules

    Directory of Open Access Journals (Sweden)

    Ruth Bärenwald

    2016-12-01

    Full Text Available The incorporation of polymers or smaller complex molecules into lipid membranes allows for property modifications or the introduction of new functional elements. The corresponding molecular-scale details, such as changes in dynamics or features of potential supramolecular structures, can be studied by a variety of solid-state NMR techniques. Here, we review various approaches to characterizing the structure and dynamics of the guest molecules as well as the lipid phase structure and dynamics by different high-resolution magic-angle spinning proton and 13C NMR experiments as well as static 31P NMR experiments. Special emphasis is placed upon the incorporation of novel synthetic polyphilic molecules such as shape-persistent T- and X-shaped molecules as well as di- and tri-block copolymers. Most of the systems studied feature dynamic heterogeneities, for instance those arising from the coexistence of different phases; possibilities for a quantitative assessment are of particular concern.

  1. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    Institute of Scientific and Technical Information of China (English)

    TIAN; JinPing

    2001-01-01

    In proton broad band decoupling 13C NMR, carbon atoms have different integration intensity because of NOE effects and their different relaxation time(T1), thus it makes a 13C NMR quantitative analyses very difficult. To acquire a 3C NMR quantitative analyses, a gated decoupling with suppressed NOE technology, i.e., an inversed gated decoupling pulse (IGDP), must be used. In IGDP relay time (tR) between two acquisition cycles must be more than 5T1, the time needed for a acquisition cycles is so long that makes the total 13C NMR quantitative analyses time much longer. For this reason, the 13C NMR quantitative analyses is paid less attention.  ……

  2. 13C NMR Quantitative Study-Part 1: Relationships between the Conformation of Amino Acids, Peptide, Carboxylic Acids and Integration Intensity of 13C NMR

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ In proton broad band decoupling 13C NMR, carbon atoms have different integration intensity because of NOE effects and their different relaxation time(T1), thus it makes a 13C NMR quantitative analyses very difficult. To acquire a 3C NMR quantitative analyses, a gated decoupling with suppressed NOE technology, i.e., an inversed gated decoupling pulse (IGDP), must be used. In IGDP relay time (tR) between two acquisition cycles must be more than 5T1, the time needed for a acquisition cycles is so long that makes the total 13C NMR quantitative analyses time much longer. For this reason, the 13C NMR quantitative analyses is paid less attention.

  3. NMR studies of the interaction between inner membrane-associated and periplasmic cytochromes from Geobacter sulfurreducens.

    Science.gov (United States)

    Dantas, Joana M; Brausemann, Anton; Einsle, Oliver; Salgueiro, Carlos A

    2017-06-01

    Geobacter sulfurreducens is a dissimilatory metal-reducing bacterium with notable properties and significance in biotechnological applications. Biochemical studies suggest that the inner membrane-associated diheme cytochrome MacA and the periplasmic triheme cytochrome PpcA from G. sulfurreducens can exchange electrons. In this work, NMR chemical shift perturbation measurements were used to map the interface region and to measure the binding affinity between PpcA and MacA. The results show that MacA binds to PpcA in a cleft defined by hemes I and IV, favoring the contact between PpcA heme IV and the MacA high-potential heme. The dissociation constant values indicate the formation of a low-affinity complex between the proteins, which is consistent with the transient interaction observed in electron transfer complexes. © 2017 Federation of European Biochemical Societies.

  4. STUDY OF THE MOLECULAR MOTION IN POLYEPICHLOROHYDRIN BY HIGH RESOLUTION NMR

    Institute of Scientific and Technical Information of China (English)

    JIA Mingchun; SHEN Lianfang; QIAN Baogong

    1993-01-01

    The molecular motion in polyepichlorohydrin (PEPCH ), in solution and bulk, was studied by high resolution NMR by means of line width, spin-lattice relaxation time T1 and nuclear Overhauser effect NOE. The results show that the VJGM model can describe the main chain motion of PEPCH in solution perfectly. In bulk state, the relationship between the line width and the temperature is consistent with WLF equation, but that between the high frequency molecular motion correlation time (in T1 scale ) and temperature is consistent with Arrhenius equation. The motion parameters of PEPCH in both states were calculated. The internal rotation motion of side -CH2C1 group was analyzed by using equal three-site jump and diffusion internal rotation model in both states.

  5. Structure and Dynamics Studies of Cytolytic Peptides in Lipid Bilayers using NMR Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Sara Krogh

    2015-01-01

    Millions of people around the world take antimicrobial drugs every day to fight off bacterial infections. However, the microbes are starting to fight back and to develop resistance towards conventional antibiotics, posing a major challenge in the future. Therefore, there is a need for exploring...... the opportunities for alternative drugs that cannot be overcome by the bacteria. In this context, cytolytic peptides are being investigated and designed to target cell membranes of microbes specifically. In the search for information about the structure and dynamics of membrane-active peptides, three highly...... to characterize different properties of these peptides. Owing to the membrane-active nature of all three, the peptides were studied in model membranes including isotropic bicelles, magnetically aligned bilayers and mechanically aligned bilayers, employing a diverse set of NMR experiments on unlabeled and 15N...

  6. 1H NMR Study of Polyvinylalcohol Irradiated by Ultra-violet

    Institute of Scientific and Technical Information of China (English)

    Xiu Ling YAN; Wan Fu SUN; Jun TANG; Xin ZHAO

    2005-01-01

    The effect of Ultra-violet light on the structure and motion of the polyvinyl alcohol(PVA) chains was studied by 1H NMR, spin-lattice relaxation and IR spectroscopy. The results indicated that with the increase of irradiation time, the intensity of the polymer hydroxyl proton peaks decreased and finally vanished, which suggested the self-condensation between the hydroxyl groups proceeded. No methyl proton peaks appeared in the spectra after irradiation shows that there is no cleavage of polymer chain. The longer the irradiation time is, the wider the proton peak of the residual water of the solvent is and it shifted toward low field. This result implies that the hydrogen bonds formed between the polymer and the residual water. The absorption peak of hydroxyl group of the polymer moves toward the lower wave number in the IR spectrum that showed the existence of the hydrogen bonds between the PVA macromolecules.

  7. 31P NMR Studies on the Ligand Dissociation of Trinuclear Molybde-num Cluster Compounds

    Institute of Scientific and Technical Information of China (English)

    李兆基; 覃业燕; 姚元根; 唐艳红; 康遥; 夏继波; 陈忠; 吴棱

    2003-01-01

    A series of carboxylate-substituted trinudear molybdenum dus-ter compounds formulated as Mo3S4(DTP)3(RCO2)(L), where RffiH, CH3, C2H5, CH2Cl, CCl3, R1C6H4(R1 is the group on the benzene ring of aromatic carboxylate ), L=pyridine,CH3CN, DMF, have been synthesized by the ligand substitu-tion reaction. The dissociation of the loosely-coordinated ligand L from the cluster core was studied by 31p NMR. The dissocia-tion process of L is related to the solvent, temperature, and acidity of carboxylate groups, so as to affect the solution struc-ture and reactive properties of the duster. The long-distance in-teraction between ligands RCO2 and L is transported by Mo3S4 core.

  8. Porous Structure of Pharmaceutical Tablets Studied Using PGSTE-NMR Technique

    Science.gov (United States)

    Porion, Patrice; Tchoreloff, Pierre; Busignies, Virginie; Leclerc, Bernard; Evesque, Pierre

    2009-06-01

    The compaction of pharmaceutical tablets at high pressure (250 MPa) is a complex process that depends on the nature of the chemical compound. The purpose of this work is to characterize the porous structure of tablets obtained by uniaxial compaction, the most used process in pharmaceutical technology. First, three pharmaceutical excipients (microcrystalline cellulose, lactose and anhydrous calcium phosphate) were compacted and their compressibility properties determined. Secondly, the study of the self-diffusion process of a molecular fluid inside the pore space was performed by using pulsed-gradient stimulated-echo (PGSTE) NMR method, for tablets compacted under various pressure, in the directions perpendicular and parallel to the compaction axis. The results are used to determine the tortuosity factor and the anisotropy of the porous space of such compacted materials.

  9. NMR studies in the half-Heusler type compound YbPtSb

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, T; Abe, M; Mito, T; Ueda, K; Kohara, T [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan); Suzuki, H S, E-mail: t-koyama@sci.u-hyogo.ac.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2011-01-01

    {sup 121}Sb and {sup 19B}Pt nuclear magnetic resonance (NMR) has been studied in the half-Heusler type compound YbPtSb to obtain information on local magnetic behavior. The characteristics of the localized 4f spins are observed in the Cuire-Weiss type behavior of the Knight shifts K for both {sup 121}Sb and {sup 19B}Pt. From the slope of K-{sub {chi}} plots we estimated hyperfine coupling constants of -3.8 and -4.6 kOe/{mu}{sub B} at Sb and Pt sites, respectively. It was found that the spin-echo decay rate 1/T{sub 2} of {sup 121}Sb shows a clear peaks at 10 K. Similar tendency was also observed in case of {sup 19B}Pt. However, static properties do not show any anomalies near 10 K.

  10. NMR strategies to study the local magnetic properties of carbon nanotubes

    KAUST Repository

    Abou-Hamad, Edy

    2012-02-01

    The local magnetic properties of the one dimensional inner space of the nanotubes are investigated using 13C nuclear magnetic resonance spectroscopy of encapsulated fullerene molecules inside single walled carbon nanotubes. Isotope engineering and magnetically purified nanotubes have been advantageously used on our study to discriminate between the different diamagnetic and paramagnetic shifts of the resonances. Ring currents originating from the π electrons circulating on the nanotube, are found to actively screen the applied magnetic field by -36.9 ppm. Defects and holes in the nanotube walls cancel this screening locally. What is interesting, that at high magnetic fields, the modifications of the NMR resonances of the molecules from free to encapsulated can be exploited to determine some structural characteristics of the surrounding nanotubes, never observed experimentally. © 2011 Elsevier B.V. All rights reserved.

  11. Study on UV, IR and NMR Spectra of Double Hydrogen-bonded Complexes

    Institute of Scientific and Technical Information of China (English)

    ZHU Liang-Liang; TENG Qi-Wen; WU Shi

    2006-01-01

    AM1, PM3 and DFT methods were used to study on the hydrogen-bonded dimer of melamine and [1,3] dioxane-2,4,6-trione. The electronic spectra, IR and NMR spectra of some complexes were calculated with INDO/SCI, AM1 and B3LYP/6-31G(d) methods, respectively. It is demonstrated that the negative stability energy is responsible for the formation of the complexes. Stabilization energies of these complexes were altered among the variations of electric property and steric effects of the monomers. HOMO-LUMO energy gaps were shrunk and the blue-shift of absorptions in the electronic spectra occurred. The vibrations of N-H bonds and chemical shifts of the protons changed with the formation of hydrogen bonds.

  12. Chain motion in poly(ethylene oxide) crystallites as studied by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Achilles, Anja; Petzold, Albrecht; Thurn-Albrecht, Thomas; Saalwachter, Kay [Institut fuer Physik, Martin-Luther-Universitaet Halle Wittenberg, Halle (Saale) (Germany)

    2008-07-01

    Many stereoregular polymers exhibit pronounced large-scale dynamics in the crystalline phase. 'Helical-jump' processes mediate chain transport over large distances through the crystallites, and they are often related to the mechanically active {alpha}{sub (c)} relaxation and macroscopic properties such as yield processes and ultradrawability. While the timescale of such processes has been studied for many different polymers, their dependence on morphological parameters, such as crystalline and amorphous layer thickness, has received less attention. In this contribution, we report on NMR investigations of helical jumps in PEO crystallites, using advanced high-resolution {sup 13}C exchange spectroscopy as well as simple analyses of the {sup 1}H time-domain signal. These results are correlated with SAXS-determined changes in the morphology and crystallinity as a function of molecular weight and the crystallization conditions.

  13. 15N NMR Spectroscopic Study on Nitrogen Formsin1mmHumic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil, alateritic red soil and a weathered coal and the effect of acidhydrolysis on N structures of soil humic substances were studied byusing {15N cross-polarization magic angle spinning nuclearmagnetic resonance (CPMAS NMR) spectroscopy. Of the detectable15N-signal intensity in the spectra of soil humic substances71%79% may be attributed to amide groups, 10%18%to aromatic/aliphatic amines and 6%11% to indole- andpyrrole-like N. Whereas in the spectrum of the fulvic acid fromweathered coal 46%, at least, of the total 15N-signalintensity might be assigned to pyrrole-like N, 14% toaromatic/aliphatic amines, and the remaining intensities could not beassigned with certainty. Data on nonhydrolyzable residue ofprotein-sugar mixture and a 15N-labelled soil fulvic acidconfirm the formation of nonhydrolyzable heterocyclic N during acidhydrolysis.

  14. NMR study on self-assembled cage complex of hexamethylenetetramine and cucurbit[n]urils

    Institute of Scientific and Technical Information of China (English)

    SHEN Yongqiang; XUE Saifeng; ZHAO Yunjie; ZHU Qianjiang; TAO Zhu

    2003-01-01

    Self-assembled complexes between cage compounds cucurbit[n = 5-8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril to forming self-assembled capsules in which nothing is encapsulated yet; the cavity of the cucurbit[7]uril can accommodate a hexamethylenetetramine molecule to form a self- assembled host-guest inclusion. Moreover, both the cavity interaction of the cucurbit[7]uril with hexamethylenetetramine·HCl and the portal interaction of the dipole carbonyl of the cucurbit[7]uril with hexamethylenetetramine·HCl lead to form self-assembled capsules in which the hexamethylenetetramine·HCl are encapsulated in the hexamethylenetetramine·HCl "lidded" cucurbit[7]uril. Although the structures of the portal and cavity to cucurbit[5]uril are similar, there is no obvious interaction between decamethylcucurbit[5]uril and hexamethylenetetramine, and also between cucurbit [6]uril or cucurbit[8]uril and hexamethylenetetramine.

  15. Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Malki, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Mekhalif, Z.; Detriche, S.; Fonder, G. [Laboratoire de Chimie et Electrochimie des Surfaces, Facultés Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, B-5000 Namur (Belgium); Boumaza, A., E-mail: charif_boumaza@yahoo.com [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Djelloul, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria)

    2014-07-01

    The changes caused by heat treatment of gibbsite powder at 300–1473 K were studied using the X-ray diffraction (XRD), X-ray photoemission (XPS) spectra and {sup 27}Al magic angle spinning nuclear magnetic resonance spectroscopy ({sup 27}Al MAS NMR). XRD analysis indicates that the transformation sequence involves the formation of κ-Al{sub 2}O{sub 3} as an intermediate phase between χ- and α-Al{sub 2}O{sub 3}. The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. XPS analysis indicates that the ratio of aluminium atoms to oxygen atoms in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3} increases, whereas the expected ratio is observed in α-Al{sub 2}O{sub 3}. The percentage of AlO{sub 4} units in the transition aluminas follows the same behaviour as the ratio of Al/O. - Graphical abstract: The percentage of AlO{sub 4} units in transition aluminas follows the same behaviour as the ratio of Al/O. - Highlights: • Calcination products of gibbsite studied by XRD, XPS and solid-state NMR. • The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. • The Al/O atomic ratio determined by XPS is larger than 2/3 in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3}. • The percentage of AlO{sub 4} in the aluminas follows the same behaviour as the Al/O atomic ratio.

  16. Membrane interactions in small fast-tumbling bicelles as studied by 31P NMR.

    Science.gov (United States)

    Bodor, Andrea; Kövér, Katalin E; Mäler, Lena

    2015-03-01

    Small fast-tumbling bicelles are ideal for studies of membrane interactions at molecular level; they allow analysis of lipid properties using solution-state NMR. In the present study we used 31P NMR relaxation to obtain detailed information on lipid head-group dynamics. We explored the effect of two topologically different membrane-interacting peptides on bicelles containing either dimyristoylphosphocholine (DMPC), or a mixture of DMPC and dimyristoylphosphoglycerol (DMPG), and dihexanoylphosphocholine (DHPC). KALP21 is a model transmembrane peptide, designed to span a DMPC bilayer and dynorphin B is a membrane surface active neuropeptide. KALP21 causes significant increase in bicelle size, as evidenced by both dynamic light scattering and 31P T2 relaxation measurements. The effect of dynorphin B on bicelle size is more modest, although significant effects on T2 relaxation are observed at higher temperatures. A comparison of 31P T1 values for the lipids with and without the peptides showed that dynorphin B has a greater effect on lipid head-group dynamics than KALP21, especially at elevated temperatures. From the field-dependence of T1 relaxation data, a correlation time describing the overall lipid motion was derived. Results indicate that the positively charged dynorphin B decreases the mobility of the lipid molecules--in particular for the negatively charged DMPG--while KALP21 has a more modest influence. Our results demonstrate that while a transmembrane peptide has severe effects on overall bilayer properties, the surface bound peptide has a more dramatic effect in reducing lipid head-group mobility. These observations may be of general importance for understanding peptide-membrane interactions.

  17. Molecular dynamics of solid benzothiadiazine derivatives (Thiazides). A study by NMR, DTA and DFT methods

    Science.gov (United States)

    Latosińska, J. N.; Latosińska, M.; Utrecht, R.; Mielcarek, S.; Pietrzak, J.

    2004-06-01

    The 1H solid state NMR spectra of four sulphonamide derivatives of 1,2,4-benzothiadiazine-1,1-dioxides (thiazides) were recorded at different temperatures in the range 100-400 K and the temperature dependencies of the second moment ( M2) of the resonant line and spin-lattice relaxation time ( T1) were measured. The minimum in the temperature dependence of the T1 revealed an activation process related to the hindered rotation (jumps) of the -NH 2 group. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points was 36.5 kJ/mol for HCTZ, 31.8 kJ/mol for ATZ, 35.2 kJ/mol for TCTZ and 40.6 kJ/mol for CTZ, and was close to that calculated by the DFT (B3LYP/6-311+G(2d,p)) method for the model assuming the -NH 2 jumps between two equilibrium positions. This type motion is responsible for the reduction in the NMR line second moment by approximately 1Gs 2 observed for all the thiazides studied. Thiazides also perform a quasi-isotropic motion tumbling whose activation energy is higher than that of the hindered jumps of the NH 2 group. This motion is characterized only by M2 reduction. According to the increasing strength of the NH 2 group bonding in the crystalline lattice, the thiazides studied can be ordered as: ATZ

  18. The Involvement of Amino Acid Side Chains in Shielding the Nickel Coordination Site: An NMR Study

    Directory of Open Access Journals (Sweden)

    Serenella Medici

    2013-10-01

    Full Text Available Coordination of proteins and peptides to metal ions is known to affect their properties, often by a change in their structural organization. Side chains of the residues directly involved in metal binding or very close to the coordination centre may arrange themselves around it, in such a way that they can, for instance, disrupt the protein functions or stabilize a metal complex by shielding it from the attack of water or other small molecules. The conformation of these side chains may be crucial to different biological or toxic processes. In our research we have encountered such behaviour in several cases, leading to interesting results for our purposes. Here we give an overview on the structural changes involving peptide side chains induced by Ni(II coordination. In this paper we deal with a number of peptides, deriving from proteins containing one or more metal coordinating sites, which have been studied through a series of NMR experiments in their structural changes caused by Ni(II complexation. Several peptides have been included in the study: short sequences from serum albumin (HSA, Des-Angiotensinogen, the 30-amino acid tail of histone H4, some fragments from histone H2A and H2B, the initial fragment of human protamine HP2 and selected fragments from prion and Cap43 proteins. NMR was the election technique for gathering structural information. Experiments performed for this purpose included 1D 1H and 13C, and 2D HSQC, COSY, TOCSY, NOESY and ROESY acquisitions, which allowed the calculation of the Ni(II complexes structural models.

  19. Non-polymeric asymmetric binary glass-formers. I. Main relaxations studied by dielectric, (2)H NMR, and (31)P NMR spectroscopy.

    Science.gov (United States)

    Pötzschner, B; Mohamed, F; Bächer, C; Wagner, E; Lichtinger, A; Minikejew, R; Kreger, K; Schmidt, H-W; Rössler, E A

    2017-04-28

    In Paper I of this series of two papers we study the main relaxations of a binary glass former made of the low-Tg component tripropyl phosphate (TPP, Tg = 134 K) and of a specially synthesized (deuterated) spirobichroman derivative (SBC, Tg = 356 K) as the non-polymeric high-Tg component for the full concentration range. A large Tg contrast of the neat components is put into effect. Dielectric spectroscopy and different techniques of (2)H nuclear magnetic resonance (NMR) as well as of (31)P NMR spectroscopy allow to selectively probe the dynamics of the components. For all concentrations, two well separated liquid-like processes are identified. The faster α2-process associated with the low-Tg component TPP shows pronounced dynamic heterogeneities reflected by quasi-logarithmic correlation functions at low TPP concentrations. The slower α1-process involves the reorientation of the high-Tg component SBC. Its correlation function is Kohlrausch-like as in neat glass formers. The corresponding time constants and consequently their glass transition temperatures Tg1 and Tg2 differ more the lower the TPP concentration is. Plasticizer and anti-plasticizer effect, respectively, is observed. At low temperatures a situation arises that the TPP molecules isotropically reorient in an arrested SBC matrix (Tg2 < T < Tg1). At T < Tg2 the liquid-like reorientation of TPP gets arrested too. We find indications that a fraction of the TPP molecule takes part in the slower α1-process of the high-Tg component. All the features known from polymer-plasticizer systems are rediscovered in this non-polymeric highly asymmetric binary mixture. In Paper II [B. Pötzschner et al., J. Chem. Phys. 146, 164504 (2017)] we study the secondary (β-) relaxations of the mixtures.

  20. Non-polymeric asymmetric binary glass-formers. I. Main relaxations studied by dielectric, 2H NMR, and 31P NMR spectroscopy

    Science.gov (United States)

    Pötzschner, B.; Mohamed, F.; Bächer, C.; Wagner, E.; Lichtinger, A.; Minikejew, R.; Kreger, K.; Schmidt, H.-W.; Rössler, E. A.

    2017-04-01

    In Paper I of this series of two papers we study the main relaxations of a binary glass former made of the low-Tg component tripropyl phosphate (TPP, Tg = 134 K) and of a specially synthesized (deuterated) spirobichroman derivative (SBC, Tg = 356 K) as the non-polymeric high-Tg component for the full concentration range. A large Tg contrast of the neat components is put into effect. Dielectric spectroscopy and different techniques of 2H nuclear magnetic resonance (NMR) as well as of 31P NMR spectroscopy allow to selectively probe the dynamics of the components. For all concentrations, two well separated liquid-like processes are identified. The faster α2-process associated with the low-Tg component TPP shows pronounced dynamic heterogeneities reflected by quasi-logarithmic correlation functions at low TPP concentrations. The slower α1-process involves the reorientation of the high-Tg component SBC. Its correlation function is Kohlrausch-like as in neat glass formers. The corresponding time constants and consequently their glass transition temperatures Tg1 and Tg2 differ more the lower the TPP concentration is. Plasticizer and anti-plasticizer effect, respectively, is observed. At low temperatures a situation arises that the TPP molecules isotropically reorient in an arrested SBC matrix (Tg2 < T < Tg1). At T < Tg2 the liquid-like reorientation of TPP gets arrested too. We find indications that a fraction of the TPP molecule takes part in the slower α1-process of the high-Tg component. All the features known from polymer-plasticizer systems are rediscovered in this non-polymeric highly asymmetric binary mixture. In Paper II [B. Pötzschner et al., J. Chem. Phys. 146, 164504 (2017)] we study the secondary (β-) relaxations of the mixtures.

  1. Near-silence of isothiocyanate carbon in (13)C NMR spectra: a case study of allyl isothiocyanate.

    Science.gov (United States)

    Glaser, Rainer; Hillebrand, Roman; Wycoff, Wei; Camasta, Cory; Gates, Kent S

    2015-05-01

    (1)H and (13)C NMR spectra of allyl isothiocyanate (AITC) were measured, and the exchange dynamics were studied to explain the near-silence of the ITC carbon in (13)C NMR spectra. The dihedral angles α = ∠(C1-C2-C3-N4) and β = ∠(C2-C3-N4-C5) describe the conformational dynamics (conformation change), and the bond angles γ = ∠(C3-N4-C5) and ε = ∠(N4-C5-S6) dominate the molecular dynamics (conformer flexibility). The conformation space of AITC contains three minima, Cs-M1 and enantiomers M2 and M2'; the exchange between conformers is very fast, and conformational effects on (13)C chemical shifts are small (νM1 - νM2 silence of the ITC carbon in (13)C NMR spectra of organic isothiocyanates.

  2. Quantitative exploitation of PFG NMR and MRI velocimetry data for the rheological study of yield stress fluid flows at macro- and micro-scales in complex geometries

    Science.gov (United States)

    Chevalier, T.; Rodts, S.; Chevalier, C.; Coussot, P.

    2015-01-01

    We explore the use of magnetic resonance imaging (MRI) velocimetry and pulsed field gradient nuclear magnetic resonance (PFG NMR) data for studying the flow characteristics of yield stress fluids through model pores (a succession of ducts of different diameters) or real porous media (bead packings). We propose different methods for the quantitative analysis of the velocity field, aimed at getting a deep understanding of the different flow regimes (solid and liquid) which typically take place in such fluids and at seeing how the transition from one to the other occurs in space or in time. Our approach exemplifies interdependences between PFG NMR data and local flow features and how the statistical velocity distribution function obtained by this way can be used and/or processed for extracting quantitative information concerning critical flow characteristics at a local scale. This provides a solid framework of analysis of flows through porous media with pores much smaller than the resolution of MR velocimetry.

  3. Dermostatin A and B: chromatography, structural and configurational studies using HPLC, CCD, 13C (125 MHz) and 1H (500 MHz) NMR spectroscopy.

    Science.gov (United States)

    Swamy, M B; Sastry, M K; Nanda, R K

    1994-01-01

    HPLC of crude Dermostatin indicated presence of three pairs of components. Hence, attempts were made to purify Dermostatin. Purification of crude Dermostatin has been carried out using column chromatography and counter current distribution methods. Each of these fractions were tested for activity. The major fraction which showed greater activity was taken for the preparation of Dermostatin nona-acetate. Structural characterisation of Dermostatin nona-acetate has been carried out using UV-visible spectroscopy in different solvents to obtain the characteristic spectrum of a carbonyl conjugated hexaene at room temperature. Structural and configurational studies of Dermostatin nona-acetate using 500 MHz 1H NMR and 125 MHz 13C NMR has been used in the assignment of various functional groups in Dermostatin A and B as well as to provide corroboration to the earlier structural elucidation.

  4. Solid-state NMR of polymers

    Energy Technology Data Exchange (ETDEWEB)

    Mirau, P

    2001-07-01

    Nuclear magnetic resonance (NMR) spectroscopy has emerged as one of the most important methods for the solid-state characterisation of polymers. The popularity of NMR is due to the fact that many molecular level features can be measured from the NMR spectra, including the polymer chain conformation, the morphology and the dynamics. The spectral features and relaxation times are affected by local interactions, so they provide information about the structure of polymers on a length scale (2-200 A) that is difficult to measure by other methods. In favourable cases, the NMR experiments provide a molecular-level explanation for the transitions observed by differential scanning calorimetry (DSC) and other methods, and the NMR properties can often be related to the bulk properties. Solid-state NMR has long been of interest in polymer science, and the first solid-state NMR studies of polymers were reported approximately a year after the discovery of nuclear resonance in bulk matter. It was reported in this initial study that the proton line width for natural rubber at room temperature is more like that of a mobile liquid than of a solid, but that the resonance broadens near the glass transition temperature (T{sub g}). This was recognised as being related to a change in chain dynamics above and below the T{sub g}. NMR methods developed rapidly after these initial observations, first for polymers in solution and, more recently, for polymers in the solid-state. Solid-state NMR studies of polymers were developed more slowly than their solution-state counterparts because solid-state NMR requires more specialised equipment. Solid-state NMR is now such an important tool that most modern spectrometers are capable of performing these studies. The interest in the NMR of solid polymers is due in part to the fact that most polymers are used in the solid state, and in many cases the NMR properties can be directly related to the macroscopic properties. Polymers have restricted mobility

  5. Structural studies of the activation of the two component receiver domain NTRC by multidimensional heteronuclear NMR

    Energy Technology Data Exchange (ETDEWEB)

    Nohaile, M J [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    Multidimensional heteronuclear NMR spectroscopy was used to investigate the N-terminal domain of the transcriptional enhancer NTRC (NiTrogen Regulatory protein C). This domain belongs to the family of receiver domains of two-component regulatory systems involved in signal transduction. Phosphorylation of NTRC at D54 leads to an activated form of the molecule which stimulates transcription of genes involved in nitrogen regulation. Three and four dimensional NMR techniques were used to determine an intermediate resolution structure of the unphosphorylated, inactive form of the N-terminal domain of NTRC. The structure is comprised of five {alpha}-helices and a five-stranded {beta}-sheet in a ({beta}/{alpha}){sub 5} topology. Analysis of the backbone dynamics of NTRC indicate that helix 4 and strand 5 are significantly more flexible than the rest of the secondary structure of the protein and that the loops making up the active site are flexible. The short lifetime of phospho-NTRC hampers the study of this form. However, conditions for determining the resonance assignments and, possibly, the three dimensional structure of phosphorylated NTRC have been obtained. Tentative assignments of the phosphorylated form indicate that the majority of the changes that NTRC experiences upon phosphorylation occur in helix 3, strand 4, helix 4, strand 5, and the loop between strand 5 and helix 5 (the 3445 face of NTRC) as well as near the site of phosphorylation. In order to examine a stable, activated form of the protein, constitutively active mutants of NTRC were investigated.

  6. 15N NMR study of nitrate ion structure and dynamics in hydrotalcite-like compounds

    Science.gov (United States)

    Hou, X.; James, Kirkpatrick R.; Yu, P.; Moore, D.; Kim, Y.

    2000-01-01

    We report here the first nuclear magnetic resonance (NMR) spectroscopic study of the dynamical and structural behavior of nitrate on the surface and in the interlayer of hydrotalcite-like compounds (15NO3--HT). Spectroscopically resolvable surface-absorbed and interlayer NO3- have dramatically different dynamical characteristics. The interlayer nitrate shows a well defined, temperature independent uniaxial chemical shift anisotropy (CS A) powder pattern. It is rigidly held or perhaps undergoes rotation about its threefold axis at all temperatures between -100 ??C and +80 ??C and relative humidities (R.H.) from 0 to 100% at room temperature. For surface nitrate, however, the dynamical behavior depends substantially on temperature and relative humidity. Analysis of the temperature and R.H. dependences of the peak width yields reorieritational frequencies which increase from essentially 0 at -100 ??C to 2.6 ?? 105 Hz at 60 ??C and an activation energy of 12.6 kJ/mol. For example, for samples at R.H. = 33%, the surface nitrate is isotropically mobile at frequencies greater than 105 Hz at room temperature, but it becomes rigid or only rotates on its threefold axis at -100 ??C. For dry samples and samples heated at 200 ??C (R.H. near 0%), the surface nitrate is not isotropically averaged at room temperature. In contrast to our previous results for 35Cl--containing hydrotalcite (35Cl--HT), no NMR detectable structural phase transition is observed for 15NO3--HT. The mobility of interlayer nitrate in HT is intermediate between that of carbonate and chloride.

  7. Structural studies of the activation of the two component receiver domain NTRC by multidimensional heteronuclear NMR

    Energy Technology Data Exchange (ETDEWEB)

    Nohaile, Michael James [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    Multidimensional heteronuclear NMR spectroscopy was used to investigate the N-terminal domain of the transcriptional enhancer NTRC (NiTrogen Regulatory protein C). This domain belongs to the family of receiver domains of two-component regulatory systems involved in signal transduction. Phosphorylation of NTRC at D54 leads to an activated form of the molecule which stimulates transcription of genes involved in nitrogen regulation. Three and four dimensional NMR techniques were used to determine an intermediate resolution structure of the unphosphorylated, inactive form of the N-terminal domain of NTRC. The structure is comprised of five α-helices and a five-stranded β-sheet in a (β/α)5 topology. Analysis of the backbone dynamics of NTRC indicate that helix 4 and strand 5 are significantly more flexible than the rest of the secondary structure of the protein and that the loops making up the active site are flexible. The short lifetime of phospho-NTRC hampers the study of this form. However, conditions for determining the resonance assignments and, possibly, the three dimensional structure of phosphorylated NTRC have been obtained. Tentative assignments of the phosphorylated form indicate that the majority of the changes that NTRC experiences upon phosphorylation occur in helix 3, strand 4, helix 4, strand 5, and the loop between strand 5 and helix 5 (the 3445 face of NTRC) as well as near the site of phosphorylation. In order to examine a stable, activated form of the protein, constitutively active mutants of NTRC were investigated.

  8. Segmental dynamics of polyethylene-alt-propylene studied by NMR spin echo techniques

    Science.gov (United States)

    Lozovoi, A.; Mattea, C.; Hofmann, M.; Saalwaechter, K.; Fatkullin, N.; Stapf, S.

    2017-06-01

    Segmental dynamics of a highly entangled melt of linear polyethylene-alt-propylene with a molecular weight of 200 kDa was studied with a novel proton nuclear magnetic resonance (NMR) approach based upon 1H → 2H isotope dilution as applied to a solid-echo build-up function ISE(t), which is constructed from the NMR spin echo signals arising from the Hahn echo (HE) and two variations of the solid-echo pulse sequence. The isotope dilution enables the separation of inter- and intramolecular contributions to this function and allows one to extract the segmental mean-squared displacements in the millisecond time range, which is hardly accessible by other experimental methods. The proposed technique in combination with time-temperature superposition yields information about segmental translation in polyethylene-alt-propylene over 6 decades in time from 10-6 s up to 1 s. The time dependence of the mean-squared displacement obtained in this time range clearly shows three regimes of power law with exponents, which are in good agreement with the tube-reptation model predictions for the Rouse model, incoherent reptation and coherent reptation regimes. The results at short times coincide with the fast-field cycling relaxometry and neutron spin echo data, yet, significantly extending the probed time range. Furthermore, the obtained data are verified as well by the use of the dipolar-correlation effect on the Hahn echo, which was developed before by the co-authors. At the same time, the amplitude ratio of the intermolecular part of the proton dynamic dipole-dipole correlation function over the intramolecular part obtained from the experimental data is not in agreement with the predictions of the tube-reptation model for the regimes of incoherent and coherent reptation.

  9. Molecular and Vibrational Dynamics in the Cholesterol-Lowering Agent Lovastatin: Solid-State NMR, Inelastic Neutron Scattering, and Periodic DFT Study.

    Science.gov (United States)

    Bilski, Paweł; Drużbicki, Kacper; Jenczyk, Jacek; Mielcarek, Jadwiga; Wąsicki, Jan

    2017-03-23

    Molecular and vibrational dynamics of a widely used cholesterol-lowering agent, lovastatin, have been studied by combining nuclear magnetic resonance relaxation experiments ((1)H NMR) with inelastic neutron scattering (INS) and periodic density functional theory modeling (plane-wave DFT). According to a complementary experimental study, lovastatin shows no phase transitions down to cryogenic conditions, while a progressive, stepwise activation of several molecular motions is observed below room temperature. The molecular packing and intermolecular forces were analyzed theoretically, supported by a (13)C NMR study and further correlated with observed molecular dynamics. The NMR relaxation experiments combined with theoretical calculations disclose that molecular dynamics in solid lovastatin is related to methyl group motions and conformational disorder in the methylbutanoate fragment. This is precisely assigned and analyzed quantitatively from both experimental and theoretical perspectives. The neutron vibrational spectroscopy further corroborates that the methyl rotors have a classical nature. In addition to the intramolecular reorientations, the vibrational dynamics was analyzed with an emphasis on the low-wavenumber range. For the first time, the terahertz response of lovastatin was studied by confronting neutron and optical techniques and clearly illustrating their complementarity. The consistent picture of the molecular dynamics is provided, which may support further considerations on alternative drug formulations and the amorphization tendency in this important lipid-lowering drug.

  10. An introduction to biological NMR spectroscopy.

    Science.gov (United States)

    Marion, Dominique

    2013-11-01

    NMR spectroscopy is a powerful tool for biologists interested in the structure, dynamics, and interactions of biological macromolecules. This review aims at presenting in an accessible manner the requirements and limitations of this technique. As an introduction, the history of NMR will highlight how the method evolved from physics to chemistry and finally to biology over several decades. We then introduce the NMR spectral parameters used in structural biology, namely the chemical shift, the J-coupling, nuclear Overhauser effects, and residual dipolar couplings. Resonance assignment, the required step for any further NMR study, bears a resemblance to jigsaw puzzle strategy. The NMR spectral parameters are then converted into angle and distances and used as input using restrained molecular dynamics to compute a bundle of structures. When interpreting a NMR-derived structure, the biologist has to judge its quality on the basis of the statistics provided. When the 3D structure is a priori known by other means, the molecular interaction with a partner can be mapped by NMR: information on the binding interface as well as on kinetic and thermodynamic constants can be gathered. NMR is suitable to monitor, over a wide range of frequencies, protein fluctuations that play a crucial role in their biological function. In the last section of this review, intrinsically disordered proteins, which have escaped the attention of classical structural biology, are discussed in the perspective of NMR, one of the rare available techniques able to describe structural ensembles. This Tutorial is part of the International Proteomics Tutorial Programme (IPTP 16 MCP).

  11. Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

    Science.gov (United States)

    Bouabdallah, Sondes; Ben Dhia, Med Thaieb; Driss, Med Rida

    2014-01-01

    The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (ΔH, ΔS, and ΔG) were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations. PMID:24707291

  12. Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

    Directory of Open Access Journals (Sweden)

    Sondes Bouabdallah

    2014-01-01

    Full Text Available The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (ΔH, ΔS, and ΔG were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations.

  13. Follicular adenomas exhibit a unique metabolic profile. ¹H NMR studies of thyroid lesions.

    Directory of Open Access Journals (Sweden)

    Stanisław Deja

    Full Text Available Thyroid cancer is the most common endocrine malignancy. However, more than 90% of thyroid nodules are benign. It remains unclear whether thyroid carcinoma arises from preexisting benign nodules. Metabolomics can provide valuable and comprehensive information about low molecular weight compounds present in living systems and further our understanding of the biology regulating pathological processes. Herein, we applied ¹H NMR-based metabolic profiling to identify the metabolites present in aqueous tissue extracts of healthy thyroid tissue (H, non-neoplastic nodules (NN, follicular adenomas (FA and malignant thyroid cancer (TC as an alternative way of investigating cancer lesions. Multivariate statistical methods provided clear discrimination not only between healthy thyroid tissue and pathological thyroid tissue but also between different types of thyroid lesions. Potential biomarkers common to all thyroid lesions were identified, namely, alanine, methionine, acetone, glutamate, glycine, lactate, tyrosine, phenylalanine and hypoxanthine. Metabolic changes in thyroid cancer were mainly related to osmotic regulators (taurine and scyllo- and myo-inositol, citrate, and amino acids supplying the TCA cycle. Thyroid follicular adenomas were found to display metabolic features of benign non-neoplastic nodules and simultaneously displayed a partial metabolic profile associated with malignancy. This finding allows the discrimination of follicular adenomas from benign non-neoplastic nodules and thyroid cancer with similar accuracy. Moreover, the presented data indicate that follicular adenoma could be an individual stage of thyroid cancer development.

  14. Chemical behavior of methylpyranomalvidin-3-O-glucoside in aqueous solution studied by NMR and UV-visible spectroscopy.

    Science.gov (United States)

    Oliveira, Joana; Petrov, Vesselin; Parola, A Jorge; Pina, Fernando; Azevedo, Joana; Teixeira, Natércia; Brás, Natércia F; Fernandes, Pedro A; Mateus, Nuno; Ramos, Maria João; de Freitas, Victor

    2011-02-17

    In the present work, the proton-transfer reactions of the methylpyranomalvidin-3-O-glucoside pigment in water with different pH values was studied by NMR and UV-visible spectroscopies. The results showed four equilibrium forms: the methylpyranomalvidin-3-O-glucoside cation, the neutral quinoidal base, the respective anionic quinoidal base, and a dianionic base unprotonated at the methyl group. According to the NMR data, it seems that for methylpyranomalvidin-3-O-glucoside besides the acid-base equilibrium between the pyranoflavylium cation and the neutral quinoidal base, a new species is formed at pD 4.88-6.10. This is corroborated by the appearance of a new set of signals in the NMR spectrum that may be assigned to the formation of hemiketal/cis-chalcone species to a small extent. The two ionization constants (pK(a1) and pK(a2)) obtained by both methods (NMR and UV-visible) for methylpyranomalvidin-3-O-glucoside are in agreement (pK(a1) = 5.17 ± 0.03; pK(a2) = 8.85 ± 0.08; and pK(a1) = 4.57 ± 0.07; pK(a2) = 8.23 ± 0.04 obtained by NMR and UV-visible spectroscopies, respectively). Moreover, the fully dianionic unprotonated form (at the methyl group) of the methylpyranomalvidin-3-O-glucoside is converted slowly into a new structure that displays a yellow color at basic pH. On the basis of the results obtained through LC-MS and NMR, the proposed structure was found to correspond to the flavonol syringetin-3-glucoside.

  15. Spin dynamics in charge doped antiferromagnets : a Li-7 NMR study in Ni1-xLixO

    NARCIS (Netherlands)

    Tedoldi, F; Marini, S; Corti, M

    1997-01-01

    The effects of heterovalent substitutions causing itinerant holes in strongly correlated 3d electron systems are studied by means of Li-7 NMR in lithium-doped antiferromagnetic NiO. The spin-lattice relaxation rates, driven by the fluctuation of Ni2+ (S = 1) ions, in the temperature range 10 K

  16. The local order of supercooled water in solution with LiCl studied by NMR proton chemical shift

    Science.gov (United States)

    Corsaro, C.; Mallamace, D.; Vasi, S.; Cicero, N.; Dugo, G.; Mallamace, F.

    2016-05-01

    We study by means of Nuclear Magnetic Resonance (NMR) spectroscopy the local order of water molecules in solution with lithium chloride at eutectic concentration. In particular, by measuring the proton chemical shift as a function of the temperature in the interval 203{ K}Widom line for water supporting the liquid-liquid transition hypothesis.

  17. Spin dynamics in charge doped antiferromagnets : a Li-7 NMR study in Ni1-xLixO

    NARCIS (Netherlands)

    Tedoldi, F; Marini, S; Corti, M

    1997-01-01

    The effects of heterovalent substitutions causing itinerant holes in strongly correlated 3d electron systems are studied by means of Li-7 NMR in lithium-doped antiferromagnetic NiO. The spin-lattice relaxation rates, driven by the fluctuation of Ni2+ (S = 1) ions, in the temperature range 10 K

  18. Spin dynamics in charge doped antiferromagnets : a Li-7 NMR study in Ni1-xLixO

    NARCIS (Netherlands)

    Tedoldi, F; Marini, S; Corti, M

    1997-01-01

    The effects of heterovalent substitutions causing itinerant holes in strongly correlated 3d electron systems are studied by means of Li-7 NMR in lithium-doped antiferromagnetic NiO. The spin-lattice relaxation rates, driven by the fluctuation of Ni2+ (S = 1) ions, in the temperature range 10 K

  19. Detailed NMR, Including 1,1-ADEQUATE, and Anticancer Studies of Compounds from the Echinoderm Colobometra perspinosa

    Directory of Open Access Journals (Sweden)

    Catherine H. Liptrot

    2009-11-01

    Full Text Available From the dichloromethane/methanol extract of the crinoid Colobometra perspinosa, collected south east of Richards Island (Bedara, Family Islands, Central Great Barrier Reef, Australia, 3-(1'-hydroxypropyl-1,6,8-trihydroxy-9,10-anthraquinone [one of the two stereoisomers of rhodoptilometrin, (1], 3-propyl-1,6,8-trihydroxy-9,10-anthraquinone (3, 2-[(phenylacetylamino]ethanesulfonic acid (4, and 4-hydroxybutanoic acid (5 were isolated. Comparison of 1H- and 13C-NMR data for rhodoptilometrin (1 with those reported in the literature showed significant differences for some resonances associated with rings A and C. In an attempt to provide accurately assigned 1H- and 13C-NMR data, as well as to confirm the structure of 1, a thorough NMR investigation of this compound was undertaken. Measurements included: concentration dependent 13C, 1D selective NOE, HSQC, HMBC and 1,1-ADEQUATE. The NMR data for 4 and 5 are reported here for the first time, as is their occurrence from the marine environment. The in vitro anticancer activity of the original extract was found to be associated with 1, 3 and 5.

  20. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    Directory of Open Access Journals (Sweden)

    S. Delbaere

    2006-01-01

    is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching obtained by UV-visible spectroscopy are reported.

  1. An NMR Study on Chrysathain%金花忍冬素的NMR数据解析

    Institute of Scientific and Technical Information of China (English)

    张剑; 李坤威; 张海艳; 陈玲; 赵天增

    2014-01-01

    Chrysathain,was isolated from Lonicera chrysatha. The 1H and 13C NMR chemical shifts of chrysathain were completely assigned using a combination of 1D NMR(1H,13C NMR and DEPT)and 2D NMR(1H-1H COSY, HSQC,HMBC and NOESY)techniques.%通过DEPT及1H-1HCOSY,HSQC,HMBC,NOESY等2D NMR技术,对从金花忍冬中分离得到的二聚体环烯醚萜苷化合物——金花忍冬素,对其1H和13C NMR信号进行了详细解析和全归属。

  2. Use of 1 H NMR to study transport processes in porous biosystems

    NARCIS (Netherlands)

    As, van H.; Lens, P.N.L.

    2001-01-01

    The operation of bioreactors and the metabolism of microorganisms in biofilms or soil/sediment systems are strongly dictated by the transport processes therein. Nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) allow nondestructive and noninvasive quantification and

  3. NMR studies of field induced magnetism in CeCoIn5

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Matthias [Los Alamos National Laboratory; Curro, Nicholas J [UC/DAVIS; Young, Ben - Li [NATIONAL CHIAO TUNG UNIV; Urbano, Ricardo R [FLORIDA STATE UNIV

    2009-01-01

    Recent Nuclear Magnetic Resonance and elastic neutron scattering experiments have revealed conclusively the presence of static incommensurate magnetism in the field-induced B phase of CeCoIns, We analyze the NMR data assuming the hyperfine coupling to the 1n(2) nuclei is anisotropic and simulate the spectra for several different magnetic structures, The NMR data are consistent with ordered Ce moments along the [001] direction, but are relatively insensitive to the direction of the incommensurate wavevector.

  4. Advanced solid-state NMR spectroscopy of natural organic matter.

    Science.gov (United States)

    Mao, Jingdong; Cao, Xiaoyan; Olk, Dan C; Chu, Wenying; Schmidt-Rohr, Klaus

    2017-05-01

    Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially a systematic approach to NOM characterization, and their applications to the study of NOM. We discuss some basics of how to acquire high-quality and quantitative solid-state (13)C NMR spectra, and address some common technical mistakes that lead to unreliable spectra of NOM. The identification of specific functional groups in NOM, primarily based on (13)C spectral-editing techniques, is described and the theoretical background of some recently-developed spectral-editing techniques is provided. Applications of solid-state NMR to investigating nitrogen (N) in NOM are described, focusing on limitations of the widely used (15)N CP/MAS experiment and the potential of improved advanced NMR techniques for characterizing N forms in NOM. Then techniques used for identifying proximities, heterogeneities and domains are reviewed, and some examples provided. In addition, NMR techniques for studying segmental dynamics in NOM are reviewed. We also briefly discuss applications of solid-state NMR to NOM from various sources, including soil organic matter, aquatic organic matter, organic matter in atmospheric particulate matter, carbonaceous meteoritic organic matter, and fossil fuels. Finally, examples of NMR-based structural models and an outlook are provided. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. A natural and readily available crowding agent: NMR studies of proteins in hen egg white.

    Science.gov (United States)

    Martorell, Gabriel; Adrover, Miquel; Kelly, Geoff; Temussi, Piero Andrea; Pastore, Annalisa

    2011-05-01

    In vitro studies of biological macromolecules are usually performed in dilute, buffered solutions containing one or just a few different biological macromolecules. Under these conditions, the interactions among molecules are diffusion limited. On the contrary, in living systems, macromolecules of a given type are surrounded by many others, at very high total concentrations. In the last few years, there has been an increasing effort to study biological macromolecules directly in natural crowded environments, as in intact bacterial cells or by mimicking natural crowding by adding proteins, polysaccharides, or even synthetic polymers. Here, we propose the use of hen egg white (HEW) as a simple natural medium, with all features of the media of crowded cells, that could be used by any researcher without difficulty and inexpensively. We present a study of the stability and dynamics behavior of model proteins in HEW, chosen as a prototypical, readily accessible natural medium that can mimic cytosol. We show that two typical globular proteins, dissolved in HEW, give NMR spectra very similar to those obtained in dilute buffers, although dynamic parameters are clearly affected by the crowded medium. The thermal stability of one of these proteins, measured in a range comprising both heat and cold denaturation, is also similar to that in buffer. Our data open new possibilities to the study of proteins in natural crowded media. Copyright © 2010 Wiley-Liss, Inc.

  6. NMR and theoretical study on interactions between diperoxovanadate complex and pyrazole-like ligands.

    Science.gov (United States)

    Yu, Xianyong; Liu, Ronghua; Peng, Hongliang; Huang, Haowen; Li, Xiaofang; Zheng, Baishu; Yi, Pinggui; Chen, Zhong

    2010-03-01

    To understand the effects of pyrazole substitution on reaction equilibrium, the interactions between a series of pyrazole-like ligands and [OV(O(2))(2)(D(2)O)](-)/[OV(O(2))(2)(HOD)](-) were explored by using multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, HSQC, and variable temperature NMR in 0.15 mol/L NaCl ionic medium mimicking physiological conditions. These results show that the relative reactivities among the pyrazole-like ligands are 3-methyl-1H-pyrazole approximately 4-methyl-1H-pyrazole approximately 1H-pyrazole>1-methyl-1H-pyrazole. As a result, the main factor which affects the reaction equilibrium is the steric effect instead of the electronic effect of the methyl group of these ligands. A pair of isomers has been formed resulting from the coordination of 3-methyl-1H-pyrazole and a vanadium complex, which is attributed to different types of coordination between the vanadium atom and the ligands. Thus, the competitive coordination leads to the formation of a series of six-coordinate peroxovanadate species [OV(O(2))(2)L](-) (L, pyrazole-like ligands). Moreover, the results of density functional calculations provided a reasonable explanation on the relative reactivity of the pyrazole-like ligands as well as the important role of solvation in these reactions.

  7. Intracellular pH and inorganic phosphate content of heart in vivo: A sup 31 P-NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Katz, L.A.; Swain, J.A.; Portman, M.A.; Balaban, R.S. (National Heart, Lung, and Blood Institute, Bethesda, MD (USA))

    1988-07-01

    Studies were performed to determine the contribution of red blood cells to the {sup 31}P-nuclear magnetic resonance (NMR) spectrum of the canine heart in vivo and the feasibility of measuring myocardial intracellular phosphate and pH. This was accomplished by replacing whole blood with a perfluorochemical perfusion emulsion blood substitute, Oxypherol, and noting the difference in the {sup 31}P-NMR spectrum of the heart. NMR data were collected with a NMR transmitter-receiver coil on the surface of the distal portion of the left ventricle. These studies demonstrated that a small contribution from 2,3-diphosphoglycerate (2,3-DPG) and phosphodiesters in the blood could be detected. The magnitude and shift of these blood-borne signals permitted the relative quantification of intracellular inorganic phosphate (P{sub i}) content as well as intracellular pH. Under resting conditions, the intracellular ATP/P{sub i} was 7.0 {plus minus} 0.08. This corresponds to a free intracellular P{sub 1} content of {approx} 0.8 {mu}mol./g wet wt. The intracellular pH was 7.10 {plus minus} 0.01. Acute respiratory alkalosis and acidosis, with the arterial pH ranging from {approximately}7.0 to 7.7, resulted in only small changes in the intracellular pH. These latter results demonstrate an effective myocardial intracellular proton-buffering mechanism in vivo.

  8. Experimental 25Mg and 13C NMR and Computational Modeling Studies of Amorphous Mg-Ca Carbonates

    Science.gov (United States)

    Singer, J. W.; Yazaydin, A. O.; Kirkpatrick, R. J.; Saharay, M.; Bowers, G. M.

    2012-12-01

    Nuclear magnetic resonance (NMR) spectroscopy of synthetic Mg-Ca amorphous carbonates (AMC-ACC) provides direct, element specific structural information about these complicated phases. The 13C, 25Mg, and 43Ca resonances are typically broad and span the chemical shift ranges of all the crystalline polymorphs in the Ca-Mg-CO3-H2O system. In a fashion similar to our previous analysis of 43Ca NMR results for ACC,1 here we integrate new experimental 13C and 25Mg spectra obtained at 20T for samples with Mg/(Ca+Mg) ratios from x=0 to x=1 with quantum chemical calculations of the NMR parameters of the crystalline phases using CASTEP calculations, simulations of the spectra using the SIMPSON software, and classical molecular dynamics calculations. XRD and 13C NMR results are in general agreement with the one-phase/two-phase model of ACC-AMC derived from thermochemical work by others.2 13C-NMR spectra of amorphous materials having intermediate compositions can not be completely fit by mechanical mixing of ACC and AMC end members—requiring a degree of Ca/Mg solid solution. Amorphous samples in two-phase region crystallize to assemblages of dolomite-like (x~0.5) and hydromagnesite-like (x~1) defective structures, but we also observe aragonite co-nucleation in the presence of excess water, indicative of a more complex evolution. While 43Ca NMR of X-ray amorphous materials shows featureless, symmetric, Gaussian line shapes, the large quadrupole moment of 25Mg gives rise to superposition of several quadrupolar line shapes representing different local structural environments. Singularities of static Mg spectra are best explained by local environments similar to nequehonite, hydromagnesite, and landsfordite. The spectra can not exclude minor contributions from anhydrous phases dolomite, huntite, and magnesite. Additional sites having very large quadrupolar coupling and/or site asymmetry are not explained by any known reference phases. CITATIONS (1) Singer, J. W.; Yazaydin, A. O

  9. Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy, a new approach to study humic material?

    Science.gov (United States)

    Knicker, Heike; Lange, Sascha; van Rossum, Barth; Oschkinat, Hartmut

    2016-04-01

    Compared to solution NMR spectroscopy, solid-state NMR spectra suffer from broad resonance lines and low resolution. This could be overcome by the use of 2-dimenstional solid-state NMR pulse sequences. Until recently, this approach has been unfeasible as a routine tool in soil chemistry, mainly because of the low NMR sensitivity of the respective samples. A possibility to circumvent those sensitivity problems represents high-field Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy (Barnes et al., 2008), allowing considerable signal enhancements (Akbey et al., 2010). This is achieved by a microwave-driven transfer of polarization from a paramagnetic center to nuclear spins. Application of DNP to MAS spectra of biological systems (frozen solutions) showed enhancements of the factor 40 to 50 (Hall et al., 1997). Enhancements of this magnitude, thus may enable the use of at least some of the 2D solid-state NMR techniques that are presently already applied for pure proteins but are difficult to apply to soil peptides in their complex matrix. After adjusting the required acquisition parameters to the system "soil organic matter", lower but still promising enhancement factors were achieved. Additional optimization was performed and allowed the acquisition of 2D 13C and 15N solid-state NMR spectra of humified 13C and 15N enriched plant residues. Within the present contribution, the first solid-state DNP NMR spectra of humic material are presented. Those data demonstrate the great potential of this approach which certainly opens new doors for a better understanding of biochemical processes in soils, sediments and water. Akbey, Ü., Franks, W.T., Linden, A., Lange, S., Griffin, R.G., van Rossum, B.-J., Oschkinat, H., 2010. Dynamic nuclear polarization of deuterated proteins. Angewandte Chemie International Edition 49, 7803-7806. Barnes, A.B., De Paëpe, G., van der Wel, P.C.A., Hu, K.N., Joo, C.G., Bajaj, V.S., Mak-Jurkauskas, M.L., Sirigiri, J.R., Herzfeld, J

  10. Ab initio study, investigation of NMR shielding tensors, NBO and vibrational frequency of catechol thioethers

    Directory of Open Access Journals (Sweden)

    A. Bagheri Gh

    2010-08-01

    Full Text Available The electrochemical oxidation of dopamine and 3,4-dihydroxymethamphetamine (HHMA has been studied in the presence of GSH and cysteine as a nucleophile. In order to determine the optimized geometries, energies, dipole moments, atomic charges, thermochemical analysis and other properties, we performed quantum chemical ab initio and density functional calculations at B3LYP level with 6-31G* basis set. The structural and vibrational properties of 5-S-glutathionyldopamine, 5-S-cysteinyldopamine and 5-S-N-acetylcysteinyldopamine are studied. The chemical shifts of anisotropy and Δδ are calculated. The gauge-invariant atomic orbital (GIAO method was employed to calculate isotropic atomic shielding of compounds. These calculations yield molecular geometries in good agreement with available experimental data. The bond lengths, bond angles, dipole moment, electron affinity, ionization potential, electronegativy, absolute hardness, highest occupied molecular orbital (HOMO and the energy of the lowest unoccupied molecular orbital (LUMO of the studied compounds were calculated in gas phase and water. NMR analysis of dopamine-o-quinone-glutathione conjugate revealed that the addition of glutathione was at C-5 to form glutathionyl-dopamine.

  11. Prostate Cancer Diagnosis: experimental and Clinical Studies With HRMAS NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stenman, Katarina

    2011-07-01

    approach using 1D and 2D high-resolution magic angle spinning (HRMAS) NMR spectroscopy combined with histopathology on intact prostatectomy specimens was evaluated in this research project. The non-destructive nature of HRMAS NMR enables spectroscopic analysis of intact tissue samples with consecutive histological examinations under light microscope. Metabolomics aids in the unraveling and the discovery of organ-specific endogenous metabolites that have the potential to be reliable indicators of organ function and viability, extrinsic and intrinsic perturbations, as well as valuable markers for treatment response. The results may, therefore, be applied clinically to characterize an organ by utilizing bio-markers that have the capacity to distinguish between disease and health. The aim was to characterize the human and the rat prostate in terms of its intermediary metabolism, which is shown here to differ between species and anatomical regions. Furthermore, the aim is to seek the verification of HRMAS NMR derived metabolites which are known to be a part of the prostate metabolome such as, citrate, choline, and the polyamines which were performed, but also the identification of metabolites not previously identified as part of the local prostate metabolism, such as Omega-6, which was detected in tumors. The extended aim was to elucidate novel bio-markers with clinical potential. In this study, the common phyto-nutrient, inositol, which appears to possess protective properties, was identified as being a potentially important PCa bio-marker for the distinction between the more indolent Gleason score 6 and the more aggressive Gleason score 7 in non-malignant prostate tissues with tumors elsewhere in the organ. Further studies in this area of PCa research are therefore warranted

  12. sup 13 C and sup 31 P NMR studies of myocardial metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Laughlin, M.R.

    1988-01-01

    The fluxes through two enzyme systems have been measured in perfused or in in vivo heart using NMR: phosphocreatine kinase, and glycogen synthase and phosphorylase. The rates of synthesis and degradation of glycogen were monitored in vivo in fed, fasted, and diabetic rat heart during infusions of {sup 13}C-1-glucose and insulin using proton-decoupled {sup 13}C-NMR at 1.9 and 4.7 tesla. The enzyme activities of glycogen synthase and glycogen phosphorylase were also measured in this tissue which had been freeze clamped at the end of the experiment, for comparison with the synthetic rates. For normal fed, fasted, and diabetic animals, synthesis rates were 0.28, 0.16, and 0.15 {mu}mol/min.gww respectively. Glycogen synthase i activity was 0.23, 0.14, and 0.14 {mu}mol/min.gww in these hearts at the end of the experiment, when measured at appropriate substrate and activator concentrations, and follow activation time courses that are consistent with being the main rate determinant for net synthesis in all cases. Turnover of glycogen was studied by observing the preformed {sup 13}C-1-glycogen signal during infusion of {sup 12}C-glucose and insulin, and was found to be close to zero. Extracted phosphorylase a activity was approximately ten times that of synthase i under these circumstances. In order to fully interpret the turnover studies, glycogenolysis of preformed {sup 13}C-glycogen was observed after a bolus of glucagon. The glycogen had either been synthesized from {sup 13}C-1-glucose for a single hour, or during an hour of {sup 13}C-glucose and a subsequent hour of {sup 12}C-glucose infusion. The author observed that breakdown follows an exponential time course related to the phosphorylase a activation state and that the last synthesized glycogen breaks down at the rate of 2.5 {mu}mol/min.gww, five times faster than that synthesized an hour earlier.

  13. Electronic properties of GeTe and Ag- or Sb-substituted GeTe studied by low-temperature 125Te NMR

    Science.gov (United States)

    Cui, J.; Levin, E. M.; Lee, Y.; Furukawa, Y.

    2016-08-01

    We have carried out 125Te nuclear magnetic resonance (NMR) in a wide temperature range of 1.5-300 K to investigate the electronic properties of Ge50Te50 ,Ag2Ge48Te50 , and Sb2Ge48Te50 from a microscopic point of view. From the temperature dependence of the NMR shift (K ) and nuclear spin lattice relaxation rate (1 /T1 ), we found that two bands contribute to the physical properties of the materials. One band overlaps the Fermi level providing the metallic state where no strong electron correlations are revealed by Korringa analysis. The other band is separated from the Fermi level by an energy gap of Eg/kB˜67 K, which gives rise to semiconductorlike properties. First-principles calculation reveals that the metallic band originates from the Ge vacancy while the semiconductorlike band is related to the fine structure of the density of states near the Fermi level. Low-temperature 125Te NMR data for the materials studied here clearly show that Ag substitution increases hole concentration while Sb substitution decreases it.

  14. β-Sheet Nanocrystalline Domains Formed from Phosphorylated Serine-Rich Motifs in Caddisfly Larval Silk: A Solid State NMR and XRD Study

    Science.gov (United States)

    Addison, J. Bennett; Ashton, Nicholas N.; Weber, Warner S.; Stewart, Russell J.; Holland, Gregory P.; Yarger, Jeffery L.

    2013-01-01

    Adhesive silks spun by aquatic caddisfly (order Trichoptera) larvae are used to build both intricate protective shelters and food harvesting nets underwater. In this study, we use 13C and 31P solid-state Nuclear Magnetic Resonance (NMR) and Wide Angle X-ray Diffraction (WAXD) as tools to elucidate molecular protein structure of caddisfly larval silk from the species Hesperophylax consimilis. Caddisfly larval silk is a fibroin protein based biopolymer containing mostly repetitive amino acid motifs. NMR and X-ray results provide strong supporting evidence for a structural model in which phosphorylated serine repeats (pSX)4 complex with divalent cations Ca2+ and Mg2+ to form rigid nanocrystalline β-sheet structures in caddisfly silk. 13C NMR data suggests that both phosphorylated serine and neighboring valine residues exist in a β-sheet secondary structure conformation while glycine and leucine residues common in GGX repeats likely reside in random coil conformations. Additionally, 31P chemical shift anisotropy (CSA) analysis indicates that the phosphates on phosphoserine residues are doubly ionized, and are charge-stabilized by divalent cations. Positively charged arginine side chains also likely play a role in charge stabilization. Finally, WAXD results finds that the silk is at least 7–8% crystalline, with β-sheet inter-plane spacings of 3.7 and 4.5 Å. PMID:23452243

  15. Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

    Science.gov (United States)

    Kamal, Ghulam Mustafa; Wang, Xiaohua; Bin Yuan; Wang, Jie; Sun, Peng; Zhang, Xu; Liu, Maili

    2016-09-01

    Soy sauce a well known seasoning all over the world, especially in Asia, is available in global market in a wide range of types based on its purpose and the processing methods. Its composition varies with respect to the fermentation processes and addition of additives, preservatives and flavor enhancers. A comprehensive (1)H NMR based study regarding the metabonomic variations of soy sauce to differentiate among different types of soy sauce available on the global market has been limited due to the complexity of the mixture. In present study, (13)C NMR spectroscopy coupled with multivariate statistical data analysis like principle component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) was applied to investigate metabonomic variations among different types of soy sauce, namely super light, super dark, red cooking and mushroom soy sauce. The main additives in soy sauce like glutamate, sucrose and glucose were easily distinguished and quantified using (13)C NMR spectroscopy which were otherwise difficult to be assigned and quantified due to serious signal overlaps in (1)H NMR spectra. The significantly higher concentration of sucrose in dark, red cooking and mushroom flavored soy sauce can directly be linked to the addition of caramel in soy sauce. Similarly, significantly higher level of glutamate in super light as compared to super dark and mushroom flavored soy sauce may come from the addition of monosodium glutamate. The study highlights the potentiality of (13)C NMR based metabonomics coupled with multivariate statistical data analysis in differentiating between the types of soy sauce on the basis of level of additives, raw materials and fermentation procedures.

  16. Modern applications of NMR tomography in physical chemistry. The characteristic features of the technique and its applications to studies of liquid-containing objects

    Energy Technology Data Exchange (ETDEWEB)

    Koptyug, Igor V; Sagdeev, Renad Z [International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2002-07-31

    This review concerns the state-of-the-art in the field of NMR tomography. The scope and limitations of the method, its capabilities, and some of the most widely used applications in physical chemistry are discussed. It is demonstrated that the technique is able to provide a vast variety of information about the state of objects under study and on the physicochemical processes occurring in them, which can be gained owing to the specific features of the technique. The review predominantly covers the studies of the structure and properties of various liquid-containing objects. The bibliography includes 232 references.

  17. Transport Properties of Ibuprofen Encapsulated in Cyclodextrin Nanosponge Hydrogels: A Proton HR-MAS NMR Spectroscopy Study.

    Science.gov (United States)

    Ferro, Monica; Castiglione, Franca; Punta, Carlo; Melone, Lucio; Panzeri, Walter; Rossi, Barbara; Trotta, Francesco; Mele, Andrea

    2016-08-15

    The chemical cross-linking of β-cyclodextrin (β-CD) with ethylenediaminetetraacetic dianhydride (EDTA) led to branched polymers referred to as cyclodextrin nanosponges (CDNSEDTA). Two different preparations are described with 1:4 and 1:8 CD-EDTA molar ratios. The corresponding cross-linked polymers were contacted with 0.27 M aqueous solution of ibuprofen sodium salt (IP) leading to homogeneous, colorless, drug loaded hydrogels. The systems were characterized by high resolution magic angle spinning (HR-MAS) NMR spectroscopy. Pulsed field gradient spin echo (PGSE) NMR spectroscopy was used to determine the mean square displacement (MSD) of IP inside the polymeric gel at different observation times td. The data were further processed in order to study the time dependence of MSD: MSD = f(td). The proposed methodology is useful to characterize the different diffusion regimes that, in principle, the solute may experience inside the hydrogel, namely normal or anomalous diffusion. The full protocols including the polymer preparation and purification, the obtainment of drug-loaded hydrogels, the NMR sample preparation, the measurement of MSD by HR-MAS NMR spectroscopy and the final data processing to achieve the time dependence of MSD are here reported and discussed. The presented experiments represent a paradigmatic case and the data are discussed in terms of innovative approach to the characterization of the transport properties of an encapsulated guest within a polymeric host of potential application for drug delivery.

  18. Metabolic profiling for studying chemotype variations in Withania somnifera (L.) Dunal fruits using GC-MS and NMR spectroscopy.

    Science.gov (United States)

    Bhatia, Anil; Bharti, Santosh K; Tewari, Shri K; Sidhu, Om P; Roy, Raja

    2013-09-01

    Withania somnifera (L.) Dunal (Solanaceae), commonly known as Ashwagandha, is one of the most valued Indian medicinal plant with several pharmaceutical and nutraceutical applications. Metabolic profiling was performed by GC-MS and NMR spectroscopy on the fruits obtained from four chemotypes of W. somnifera. A combination of (1)H NMR spectroscopy and GC-MS identified 82 chemically diverse metabolites consisting of organic acids, fatty acids, aliphatic and aromatic amino acids, polyols, sugars, sterols, tocopherols, phenolic acids and withanamides in the fruits of W. somnifera. The range of metabolites identified by GC-MS and NMR of W. somnifera fruits showed various known and unknown metabolites. The primary and secondary metabolites observed in this study represent MVA, DOXP, shikimic acid and phenylpropanoid biosynthetic metabolic pathways. Squalene and tocopherol have been rated as the most potent naturally occurring compounds with antioxidant properties. These compounds have been identified by us for the first time in the fruits of W. somnifera. Multivariate principal component analysis (PCA) on GC-MS and NMR data revealed clear distinctions in the primary and secondary metabolites among the chemotypes. The variation in the metabolite concentration among different chemotypes of the fruits of W. somnifera suggest that specific chemovars can be used to obtain substantial amounts of bioactive ingredients for use as potential pharmacological and nutraceuticals agents.

  19. Study of Low Molecular Weight Impurities in Pluronic Triblock Copolymers using MALDI, Interaction Chromatography, and NMR

    Science.gov (United States)

    Helming, Z.; Zagorevski, D.; Ryu, C. Y.

    2014-03-01

    Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers are a group of commercial macromolecular amphiphilic surfactants that have been widely studied for their applications in polymer-based nanotechnology and drug-delivery. It has been well-established that the synthesis of commercial Pluronic triblocks results in low molecular weight ``impurities,'' which are generally disregarded in the applications and study of these polymers. These species have been shown to have significant effects on the rheological properties of the material, as well as altering the supramolecular ``micellar'' structures for which the polymers are most often used. We have isolated the impurities from the bulk Pluronic triblock using Interaction Chromatography (IC) techniques, and subjected them to analysis by H1 NMR and MALDI (Matrix-Assisted Laser Desorption Ionization) Mass Spectrometry to identify relative block composition and molecular weight information. We report significant evidence of at least two polymeric components: a low-molecular-weight homopolymer of poly(ethylene oxide) and a ``blocky'' copolymer of both poly(ethylene oxide) and poly(propylene oxide). This has significant implications, not only for the applied usage of Pluronic triblock copolymers, but for the general scientific acceptance of the impurities and their effects on Pluronic micelle and hydrogel formation.

  20. NMR studies of DNA oligomers and their interactions with minor groove binding ligands

    Energy Technology Data Exchange (ETDEWEB)

    Fagan, Patricia A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    The cationic peptide ligands distamycin and netropsin bind noncovalently to the minor groove of DNA. The binding site, orientation, stoichiometry, and qualitative affinity of distamycin binding to several short DNA oligomers were investigated by NMR spectroscopy. The oligomers studied contain A,T-rich or I,C-rich binding sites, where I = 2-desaminodeoxyguanosine. I•C base pairs are functional analogs of A•T base pairs in the minor groove. The different behaviors exhibited by distamycin and netropsin binding to various DNA sequences suggested that these ligands are sensitive probes of DNA structure. For sites of five or more base pairs, distamycin can form 1:1 or 2:1 ligand:DNA complexes. Cooperativity in distamycin binding is low in sites such as AAAAA which has narrow minor grooves, and is higher in sites with wider minor grooves such as ATATAT. The distamycin binding and base pair opening lifetimes of I,C-containing DNA oligomers suggest that the I,C minor groove is structurally different from the A,T minor groove. Molecules which direct chemistry to a specific DNA sequence could be used as antiviral compounds, diagnostic probes, or molecular biology tools. The author studied two ligands in which reactive groups were tethered to a distamycin to increase the sequence specificity of the reactive agent.

  1. A REDOR NMR Study of a Phosphorylated Statherin Fragment Bound to Hydroxyapatite Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, James M.; Raghunathan, Vinodhkumar; Popham, Jennifer M.; Stayton, Patrick; Drobny, Gary P.

    2005-06-09

    Acidic proteins found in mineralized tissues act as nature's crystal engineers, where they play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), Ca10(PO4)6- (OH)2, the main mineral component of bone and teeth. There is remarkably little known about the protein structure-function relationships and the recognition processes governing hard tissue engineering. It is well-known that several salivary proteins (statherin) and peptides (SN-15, N-terminal 15 amino fragment of statherin) bind strongly to HAP to regulate crystal growth.1 In this work, we describe how solid-state NMR can be used to identify which amino acid side chains of SN-15 (DpSpSEE15NKFLRRIGRFG) interact with the HAP surface, even in the presence of phosphorylated side chains. Prior structural studies have indicated that the second through twelfth amino acids are R-helical in full length statherin on HAP, while the SN-15 fragment is in an extended structure toward the N-terminus, only gaining R-helical structure at the seventh amino acid. Additionally, prior dynamics studies have indicated that the region from the seventh amino acid to the C-terminus interacts less strongly with the HAP surface than the first six amino acids.

  2. (31)P NMR study of post mortem changes in pig muscle.

    Science.gov (United States)

    Miri, A; Talmant, A; Renou, J P; Monin, G

    1992-01-01

    The rate and the extent of post mortem pH changes in pig muscle largely determine pork quality. Fast pH fall combined with low ultimate pH leads to pale soft exudative (PSE) meat; high ultimate pH leads to dark firm dry (DFD) meat. Post mortem metabolism was studied in pig muscle using(31)P NMR. Fifteen pigs, i.e. 7 Large White pigs and 8 Pietrain pigs, were used. Five pigs of each breed were slaughtered, taking care to minimize preslaughter stress. The other pigs (3 Large Whites and 2 Pietrains) were injected with 0·1 mg adrenaline per kg liveweight before slaughter, in order to increase meat ultimate pH. All the animals were killed by electronarcosis and exsanguination. Three of the adrenaline-treated pigs (1 Large White and 2 Pietrains) gave meat with ultimate pH above 6 (DFD meat). The pigs with normal muscle ultimate pH, i.e. 6 Large Whites and 6 Pietrains, had very variable rates of post mortem muscle metabolism (pH at 30 min after slaughter: 6·17-6·85 in Large Whites; 6·04-6·23 in Pietrains). The relationships between pH and ATP changes were similar in all pigs showing normal muscle ultimate pH, whereas ATP disappeared at a high pH value (on average pH 6·4) in pigs with high ultimate pH. The course of post mortem biochemical changes in a given animal could be predicted rather well by examination of a single(31)P NMR spectrum obtained around 30 min after death. At this time, muscle with a low rate of metabolism simultaneously showed medium to high pH, high ATP content (4-6·8 μmol/g) and rather low Pi content (6-14 μmol/g); muscle with a fast rate of metabolism (PSE-prone muscle) had low pH, low to medium ATP content (1·1-4 μmol/g) and generally high phosphomonoester (PME) content (9-23 μmol/g); muscle with high ultimate pH (DFD-prone muscle) had high pH, low PME content (4-8 μmol/g) and high Pi content (22-27 μmol/g).

  3. Homonuclear and Heteronuclear NMR Studies of a Statherin Fragment Bound to Hydroxyapatite Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Raghunathan, Vinodhkumar; Gibson, James M.; Goobes, Gil; Popham, Jennifer M.; Louie, Elizabeth; Stayton, Patrick; Drobny, Gary P.

    2006-05-11

    Acidic proteins found in mineralized tissues act as nature's crystal engineers, where they play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), Ca10(PO4)6(OH)2, the main mineral component of bone and teeth. Key to understanding the structural basis of protein-crystal recognition and protein control of hard tissue growth is the nature of interactions between the protein side chains and the crystal surface. In an earlier work we have measured the proximity of the lysine (K6) side chain in an SN-15 peptide fragment of the salivary protein statherin adsorbed to the Phosphorus-rich surface of HAP using solid-state NMR recoupling experiments. 15N(31P) rotational echo double resonance (REDOR) NMR data on the side-chain nitrogen in K6 gave rise to three different models of protein-surface interaction to explain the experimental data acquired. In this work we extend the analysis of the REDOR data by examining the contribution of interactions between surface phosphorus atoms to the observed 15N REDOR decay. We performed 31P-31P recoupling experiments in HAP and (NH4)2HPO4 (DHP) to explore the nature of dipolar coupled 31P spin networks. These studies indicate that extensive networks of dipolar coupled 31P spins can be represented as stronger effective dipolar couplings, the existence of which must be included in the analysis of REDOR data. We carried out 15N(31P) REDOR in the case of DHP to determine how the size of the dephasing spin network influences the interpretation of the REDOR data. Although use of an extended 31P coupled spin network simulates the REDOR data well, a simplified 31P dephasing system composed of two spins with a larger dipolar coupling also simulates the REDOR data and only perturbs the heteronuclear couplings very slightly. The 31P-31P dipolar couplings between phosphorus nuclei in HAP can be replaced by an effective dipolar interaction of 600 Hz between two 31P spins. We incorporated this coupling and

  4. NMR-based metabolite profiling of human milk: A pilot study of methods for investigating compositional changes during lactation.

    Science.gov (United States)

    Wu, Junfang; Domellöf, Magnus; Zivkovic, Angela M; Larsson, Göran; Öhman, Anders; Nording, Malin L

    2016-01-15

    Low-molecular-weight metabolites in human milk are gaining increasing interest in studies of infant nutrition. In the present study, the milk metabolome from a single mother was explored at different stages of lactation. Metabolites were extracted from sample aliquots using either methanol/water (MeOH/H2O) extraction or ultrafiltration. Nuclear magnetic resonance (NMR) spectroscopy was used for metabolite identification and quantification, and multi- and univariate statistical data analyses were used to detect changes over time of lactation. Compared to MeOH/H2O extraction, ultrafiltration more efficiently reduced the interference from lipid and protein resonances, thereby enabling the identification and quantification of 36 metabolites. The human milk metabolomes at the early (9-24 days after delivery) and late (31-87 days after delivery) stages of lactation were distinctly different according to multi- and univariate statistics. The late lactation stage was characterized by significantly elevated concentrations of lactose, choline, alanine, glutamate, and glutamine, as well as by reduced levels of citrate, phosphocholine, glycerophosphocholine, and N-acetylglucosamine. Our results indicate that there are significant compositional changes of the human milk metabolome also in different phases of the matured lactation stage. These findings complement temporal studies on the colostrum and transitional metabolome in providing a better understanding of the nutritional variations received by an infant.

  5. An advanced phantom study assessing the feasibility of neuronal current imaging by ultra-low-field NMR

    Science.gov (United States)

    Körber, Rainer; Nieminen, Jaakko O.; Höfner, Nora; Jazbinšek, Vojko; Scheer, Hans-Jürgen; Kim, Kiwoong; Burghoff, Martin

    2013-12-01

    In ultra-low-field (ULF) NMR/MRI, a common scheme is to magnetize the sample by a polarizing field of up to hundreds of mT, after which the NMR signal, precessing in a field on the order of several μT, is detected with superconducting quantum interference devices (SQUIDs). In our ULF-NMR system, we polarize with up to 50 mT and deploy a single-stage DC-SQUID current sensor with an integrated input coil which is connected to a wire-wound Nb gradiometer. We developed this system (white noise 0.50 fT/√{Hz}) for assessing the feasibility of imaging neuronal currents by detecting their effect on the ULF-NMR signal. Magnetoencephalography investigations of evoked brain activity showed neuronal dipole moments below 50 nAm. With our instrumentation, we have studied two different approaches for neuronal current imaging. In the so-called DC effect, long-lived neuronal activity shifts the Larmor frequency of the surrounding protons. An alternative strategy is to exploit fast neuronal activity as a tipping pulse. This so-called AC effect requires the proton Larmor frequency to match the frequency of the neuronal activity, which ranges from near-DC to ∼kHz. We emulated neuronal activity by means of a single dipolar source in a physical phantom, consisting of a hollow sphere filled with an aqueous solution of CuSO4 and NaCl. In these phantom studies, with physiologically relevant dipole depths, we determined resolution limits for our set-up for the AC and the DC effect of ∼10 μAm and ∼50 nAm, respectively. Hence, the DC effect appears to be detectable in vivo by current ULF-NMR technology.

  6. Incorporation of antimicrobial peptides into membranes: a combined liquid-state NMR and molecular dynamics study of alamethicin in DMPC/DHPC bicelles.

    Science.gov (United States)

    Dittmer, Jens; Thøgersen, Lea; Underhaug, Jarl; Bertelsen, Kresten; Vosegaard, Thomas; Pedersen, Jan M; Schiøtt, Birgit; Tajkhorshid, Emad; Skrydstrup, Troels; Nielsen, Niels Chr

    2009-05-14

    Detailed insight into the interplay between antimicrobial peptides and biological membranes is fundamental to our understanding of the mechanism of bacterial ion channels and the action of these in biological host-defense systems. To explore this interplay, we have studied the incorporation, membrane-bound structure, and conformation of the antimicrobial peptide alamethicin in lipid bilayers using a combination of 1H liquid-state NMR spectroscopy and molecular dynamics (MD) simulations. On the basis of experimental NMR data, we evaluate simple in-plane and transmembrane incorporation models as well as pore formation for alamethicin in DMPC/DHPC (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine/1,2-dihexanoyl-sn-glycero-3-phosphatidylcholine) bicelles. Peptide-lipid nuclear Overhauser effect (NOE) and paramagnetic relaxation enhancement (PRE) data support a transmembrane configuration of the peptide in the bilayers, but they also reveal that the system cannot be described by a single simple conformational model because there is a very high degree of dynamics and heterogeneity in the three-component system. To explore the origin of this heterogeneity and dynamics, we have compared the NOE and PRE data with MD simulations of an ensemble of alamethicin peptides in a DMPC bilayer. From all-atom MD simulations, the contacts between peptide, lipid, and water protons are quantified over a time interval up to 95 ns. The MD simulations provide a statistical base that reflects our NMR data and even can explain some initially surprising NMR results concerning specific interactions between alamethicin and the lipids.

  7. Providers' response to child eating behaviors: A direct observation study.

    Science.gov (United States)

    Tovar, Alison; Vaughn, Amber E; Fallon, Megan; Hennessy, Erin; Burney, Regan; Østbye, Truls; Ward, Dianne S

    2016-10-01

    Child care providers play an important role in feeding young children, yet little is known about children's influence on providers' feeding practices. This qualitative study examines provider and child (18 months -4 years) feeding interactions. Trained data collectors observed 200 eating occasions in 48 family child care homes and recorded providers' responses to children's meal and snack time behaviors. Child behaviors initiating provider feeding practices were identified and practices were coded according to higher order constructs identified in a recent feeding practices content map. Analysis examined the most common feeding practices providers used to respond to each child behavior. Providers were predominately female (100%), African-American (75%), and obese (77%) and a third of children were overweight/obese (33%). Commonly observed child behaviors were: verbal and non-verbal refusals, verbal and non-verbal acceptance, being "all done", attempts for praise/attention, and asking for seconds. Children's acceptance of food elicited more autonomy supportive practices vs. coercive controlling. Requests for seconds was the most common behavior, resulting in coercive controlling practices (e.g., insisting child eat certain food or clean plate). Future interventions should train providers on responding to children's behaviors and helping children become more aware of internal satiety and hunger cues.

  8. Benford distributions in NMR

    CERN Document Server

    Bhole, Gaurav; Mahesh, T S

    2014-01-01

    Benford's Law is an empirical law which predicts the frequency of significant digits in databases corresponding to various phenomena, natural or artificial. Although counter intuitive at the first sight, it predicts a higher occurrence of digit 1, and decreasing occurrences to other larger digits. Here we report the Benford analysis of various NMR databases and draw several interesting inferences. We observe that, in general, NMR signals follow Benford distribution in time-domain as well as in frequency domain. Our survey included NMR signals of various nuclear species in a wide variety of molecules in different phases, namely liquid, liquid-crystalline, and solid. We also studied the dependence of Benford distribution on NMR parameters such as signal to noise ratio, number of scans, pulse angles, and apodization. In this process we also find that, under certain circumstances, the Benford analysis can distinguish a genuine spectrum from a visually identical simulated spectrum. Further we find that chemical-sh...

  9. 27 Al MAS NMR Studies of HBEA Zeolite at Low to High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Wan, Chuan; Vjunov, Aleksei; Wang, Meng; Zhao, Zhenchao; Hu, Mary Y.; Camaioni, Donald M.; Lercher, Johannes A.

    2017-06-01

    27Al single pulse (SP) MAS NMR spectra of HBEA zeolites with high Si/Al ratios of 71 and 75 were obtained at three magnetic field strengths of 7.05, 11.75 and 19.97 T. High field 27Al MAS NMR spectra acquired at 19.97 T show significantly improved spectral resolution, resulting in at least two well-resolved tetrahedral-Al NMR peaks. Based on the results obtained from 27Al MAS and MQMAS NMR acquired at 19.97 T, four different quadrupole peaks are used to deconvolute the 27Al SP MAS spectra acquired at vari-ous fields by using the same set of quadrupole coupling constants, asymmetric parameters and relative integrated peak intensities for the tetrahedral Al peaks. The line shapes of individual peaks change from typical quadrupole line shape at low field to essentially symmetrical line shapes at high field. We demonstrate that for fully hydrated HBEA zeolites the effect of second order quadrupole interaction can be ignored and quantitative spectral analysis can be performed by directly fitting the high field spectra using mixed Gaussian/Lorentzian line shapes. Also, the analytical steps described in our work allow direct assignment of spectral intensity to individual Al tetrahedral sites (T-sites) of zeolite HBEA. Finally, the proposed concept is suggested generally applicable to other zeo-lite framework types, thus, allowing a direct probing of Al distributions by NMR spectroscopic methods in zeolites with high confi-dence.

  10. Solid-state (17)O NMR study of 2-acylbenzoic acids and warfarin.

    Science.gov (United States)

    Kong, Xianqi; Dai, Yizhe; Wu, Gang

    We report synthesis and solid-state (17)O NMR characterization of four site-specifically (17)O-labeled 2-acylbenzoic acids (2-RC(O)C6H4COOH) where R=H and CH3): 2-[3-(17)O]formylbenzoic acid, 2-[1,2-(17)O2]formylbenzoic acid, 2-[3-(17)O]acetylbenzoic acid, and 2-[1,2,3-(17)O3]acetylbenzoic acid. In the solid state, both 2-formyl- and 2-acetyl-benzoic acids exist as the cyclic phthalide form each containing a five-membered lactone ring and a cyclic hemiacetal/hemiketal group. Static and magic-angle-spinning (17)O NMR spectra were recorded at 14.1 and 21.1T for these compounds, from which the (17)O chemical shift and nuclear quadrupolar coupling tensors were determined for each oxygen site. These results represent the first time that (17)O NMR tensors are fully characterized for lactone, cyclic hemiacetal, and cyclic hemiketal functional groups. We also report solid-state (17)O NMR data for the cyclic hemiketal group an anticoagulant drug, warfarin. Experimental (17)O NMR tensors in these compounds were compared with computational results obtained with a periodic DFT code BAND. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Thermodynamic Study on the Protonation Reactions of Glyphosate in Aqueous Solution: Potentiometry, Calorimetry and NMR spectroscopy.

    Science.gov (United States)

    Liu, Bijun; Dong, Lan; Yu, Qianhong; Li, Xingliang; Wu, Fengchang; Tan, Zhaoyi; Luo, Shunzhong

    2016-03-10

    Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject (J. Phys. Chem. A 2015, 119, 5241-5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7-8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.

  12. Conformational preferences of proline derivatives incorporated into vasopressin analogues: NMR and molecular modelling studies.

    Science.gov (United States)

    Sikorska, Emilia; Sobolewski, Dariusz; Kwiatkowska, Anna

    2012-04-01

    In this study, arginine vasopressin analogues modified with proline derivatives - indoline-2-carboxylic acid (Ica), (2S,4R)-4-(naphthalene-2-ylmethyl)pyrrolidine-2-carboxylic acid (Nmp), (2S,4S)-4-aminopyroglutamic acid (APy) and (2R,4S)-4-aminopyroglutamic acid, (Apy) - were examined using NMR spectroscopy and molecular modelling methods. The results have shown that Ica is involved in the formation of the cis peptide bond. Moreover, it reduces to a great extent the conformational flexibility of the peptide. In turn, incorporation of (2S,4R)-Nmp stabilizes the backbone conformation, which is heavily influenced by the pyrrolidine ring. However, the aromatic part of the Nmp side chain exhibits a high degree of conformational freedom. With analogues IV and V, introduction of the 4-aminopyroglumatic acid reduces locally conformational space of the peptides, but it also results in weaker interactions with the dodecylphosphocholine/sodium dodecyl sulphate micelle. Admittedly, both analogues are adsorbed on the micelle's surface but they do not penetrate into its core. With analogue V, the interactions between the peptide and the micelle seem to be so weak that conformational equilibrium is established between different bound states.

  13. GC-FID and NMR Spectroscopic Studies on Gamma Irradiated Walnut Lipids

    Directory of Open Access Journals (Sweden)

    Vassilia J. Sinanoglou

    2015-01-01

    Full Text Available Walnuts have an excellent fatty acid profile, beneficial for coronary heart diseases. A diet rich in walnuts has shown to decrease the total and LDL cholesterol levels as well as lipoprotein levels. In this study, the effects of different doses of γ-irradiation and different packaging conditions on proximate composition and fatty acid profile of walnuts (Juglans regia L. were investigated merging data from different spectroscopic techniques. Walnuts moisture, ash, fat, and protein content as well as fatty acid profile were evaluated immediately after irradiation. GC-FID results showed that SFA increased and MUFA and PUFA decreased with the increase of irradiation dose. Moreover, MUFA/SFA and PUFA/SFA ratios decreased P<0.05 compared to control samples. Furthermore, NMR spectroscopy was implemented to examine possible discrimination patterns based on irradiation dose and packaging. This approach revealed the role of PUFA decrease with the parallel increase of irradiation dose while indicating the protective role of vacuum and MAP compared to air packaging. In conclusion, at irradiation doses of up to 5 kGy, the walnuts retained the nutritional benefits of its fatty acids, in particular MUFA and PUFA. Concerning the different types of packaging, greater stability in the nuts was observed using MAP packaging.

  14. 31P NMR studies on the effect of phosphite on Phytophthora palmivora.

    Science.gov (United States)

    Niere, J O; Griffith, J M; Grant, B R

    1990-01-01

    31P NMR spectra were obtained from perchloric acid (PCA) and KOH extracts of Phytophthora palmivora mycelium. Signals indicating the presence of large amounts of short-chain polyphosphate were observed in the spectra of PCA extracts of mycelia grown under both low (0.1 mM) and high (10 mM) phosphate conditions. The mean chain length of polyphosphate was calculated from the relative areas of signals arising from terminal and internal P nuclei in the polyphosphate chain. The small amount of polyphosphate evident in the KOH extract had an average chain length similar to PCA-soluble polyphosphate. 32P tracer studies indicated that phosphorus in the PCA fraction accounted for between 50 and 60% of total phosphorus, the bulk of the remainder being divided between the lipid and KOH extracts. The presence of the fungicide phosphorous acid markedly reduced the average chain length of acid-soluble polyphosphate. This reduction occurred both under low-phosphate conditions, in which treatment with phosphorous acid retards growth, and under high-phosphate conditions, in which no significant growth retardation is observed. Treatment with phosphorous acid perturbed phosphorus distribution and lipid composition under low-phosphate conditions.

  15. Solid state 1H NMR studies of cell wall materials of potatoes

    Science.gov (United States)

    Tang, Huiru; Belton, Peter S.; Ng, Annie; Waldron, Keith W.; Ryden, Peter

    1999-04-01

    Cell wall materials from potatoes ( Solanum tuberosum) prepared by two different methods have been studied using NMR proton relaxation times. Spin lattice relaxation in both the rotating and laboratory frames as well as transverse relaxation have been measured over a range of temperatures and hydration levels. It was observed that the sample prepared using a DMSO extraction showed anomalous behaviour of spin lattice relaxation in the laboratory frame probably due to residual solvent in the sample. Spin lattice relaxation in the laboratory frame is the result of hydroxymethyl rotation and another unidentified high frequency motion. In the rotating frame relaxation is adequately explained by hydroxymethyl rotation alone. In neither experiment is methyl group rotation observed, calculation suggests that this is due to the low density of methyl groups in the sample. Non-freezing water in potato cell walls, α-cellulose and pectin was found about 0.2, 0.04 and 0.18 g per gram dry matter, indicating preferable hydration of pectin compared to cellulose. The effects of hydration are most noticeable in the measurements that reflect low frequency motions, particularly transverse relaxation, where both second moments and the relative intensity of signals arising from immobile material are reduced by hydration.

  16. Study on Nitrogen Forms in Phenolic Polymers Incorporating Protien by 15N CP—MAS NMR

    Institute of Scientific and Technical Information of China (English)

    CHENGLILI; WENQIXIAO; 等

    1996-01-01

    Phenolic polymers synthesized by reactions by reactions of p-benzoquinone with 15N-labelled protein or (15NH4)2SO4 were studied by using 15N CP-MAS NMR technique in combination with chemical approaches.Results showed that more than 80% of nitrogen in quinone-protein polymers was in the form of amide with some present as aromatic and /or aliphatic amine and less than 10% of nitrogen occurred as heterocyclic N.The nitrogen distribution in the non-hydrolyzable residue of the quinone-protein polymers was basically similar to that of soil humic acid reported in literature with the exception that a higher proportion of N as heterocyclic N and aromatic amine and a lower proportion of N as amide and aliphatic amine were found in the former than in the latter,More than 70% of total nitrogen in quinone-(NH4)2OS4 polymer was acid resistant ,of which about 53% occurred as pyrrole,nitrile and imion type N.The possible roles of the reactions of phenols or quinones with proteins in the formation of humic acid.especially the non-hydrolyzable nitrogen in humicacid,are discussed.

  17. 15N NMR Spectroscopic Study on Nitrogen Forms in Humic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    WENQIXAIO; ZHUOSUNENG; 等

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil,a lateritic red soil and a weathered cola and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance(CPMAS NMR) spectroscopy,Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups ,10%-18% to aromatic/aliphatic amines and 6%-11% to indole-and pyrrole-like N.Whereas in the spectrum of the fulvic acid from weathered coal 46%,at least,of the total 15N-signal intensity might be assigned to pyrrole-like N,14% to aromatic/aliphatic amines,and the reamining intensities could not be assigned with certainty,Data on nonhydrolyzable reside of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis.

  18. sup 1 sup 1 B nutation NMR study of powdered borosilicates

    CERN Document Server

    Woo, A J; Han, D Y

    1998-01-01

    In this work, we applied the 1D sup 1 sup 1 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO sub 2 -B sub 2 O sub 3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D sup 1 sup 1 B nutation NMR experiment. The sup 1 sup 1 B NMR parameters, quadrupole coupling constants (e sup 2 qQ/h) and asymmetry parameters (eta), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

  19. NMR study of pyrochlore lattice antiferromagnet, melanothallite Cu2OCl2

    Science.gov (United States)

    Nishiyama, Masahide; Oyamada, Akira; Itou, Tetsuaki; Maegawa, Satoru; Okabe, Hirotaka; Akimitsu, Jun

    2011-09-01

    The melanothallite Cu2OCl2 is a new example of pyrochlore-like antiferromagnet, which is composed of 3d transition metal electrons. We performed Cu- and Cl-NMR experiments on powder samples of Cu2OCl2 below transition temperature TN = 70 K and we observed six resonant peaks of Cu nuclei, which are composed of three symmetric peaks corresponding to 63Cu and three corresponding to 65Cu. The Cu nuclei feel the strong hyperfine fields because of ordered magnetic moments and the electric field gradients. We determined the spin structure by analyzing the Cu-NMR spectra. The melanothallite has an all-in-all-out spin structure. The spin lattice relaxation rates T1-1 of Cu- and Cl-NMR in the ordered phase are proportional to the temperature; This suggests that although long-range ordering occurs at rather high temperature, the large spin fluctuations caused by the geometrical frustration still remain.

  20. NMR studies of the conformation of the natural sweetener rebaudioside A.

    Science.gov (United States)

    Steinmetz, Wayne E; Lin, Alvin

    2009-12-14

    Rebaudioside A is a natural sweetener from Stevia rebaudiana in which four beta-D-glucopyranose units are attached to the aglycone steviol. Its (1)H and (13)C NMR spectra in pyridine-d(5) were assigned using 1D and 2D methods. Constrained molecular dynamics of solvated rebaudioside using NMR constraints derived from ROESY cross peaks yielded the orientation of the beta-D-glucopyranose units. Hydrogen bonding was examined using the temperature coefficients of the hydroxyl chemical shifts, ROESY and long-range COSY spectra, and proton-proton coupling constants.

  1. NMR Study on the Inclusion Complexes of β-Cyclodextrin with Isoflavones

    OpenAIRE

    Rui Zhao; Corine Sandström; Haiyang Zhang; Tianwei Tan

    2016-01-01

    The structure of the inclusion complexes of β-cyclodextrin (β-CD) with daidzein and daidzin in D2O were investigated using NMR spectroscopy. For the β-CD and daidzein system, two types of 1:1 complexes were formed with the daidzein deeply inserted into the CD cavity with different orientations. For the β-CD/daidzin system, a 1:1 complex was formed with the flavonoid part of daidzin entering the CD cavity from the wide rim. The inclusion complexes determined by NMR were constructed using molec...

  2. Vibrational spectra, NMR and theoretical studies of the enantiomers and rotamers of alpha-cypermethrin

    Science.gov (United States)

    Jubert, Alicia H.; Alegre, María L.; Diez, Reinaldo Pis; Pomilio, Alicia B.; Szewczuk, Víctor D.

    2007-04-01

    NMR, infrared and Raman vibrational spectra of alpha-cypermethrin have been measured at room temperature. Infrared spectra were also recorded to low temperature. The spectra were analyzed by means of ab initio calculations. The conformational space of both enantiomers and some rotamers A, B and C of alpha-cypermethrin has been scanned using molecular dynamics and complemented with functional density calculations that optimize the geometry of the lowest-energy conformers of each species as obtained in the simulations. The vibrational frequencies and the 1H and 13C NMR chemical shifts were assigned using functional density calculations. The molecular electrostatic potential maps were obtained and analyzed.

  3. (13)C and (15)N solid-state NMR studies on albendazole and cyclodextrin albendazole complexes.

    Science.gov (United States)

    Ferreira, M João G; García, A; Leonardi, D; Salomon, Claudio J; Lamas, M Celina; Nunes, Teresa G

    2015-06-05

    (13)C and (15)N solid-state nuclear magnetic resonance (NMR) spectra were recorded from albendazole (ABZ) and from ABZ:β-cyclodextrin, ABZ:methyl-β-cyclodextrin, ABZ:hydroxypropyl-β-cyclodextrin and ABZ:citrate-β-cyclodextrin, which were prepared by the spray-drying technique. ABZ signals were typical of a crystalline solid for the pure drug and of an amorphous compound obtained from ABZ:cyclodextrin samples. Relevant spectral differences were correlated with chemical interaction between ABZ and cyclodextrins. The number and type of complexes revealed a strong dependence on the cyclodextrin group substituent. Solid-state NMR data were consistent with the presence of stable inclusion complexes.

  4. {sup 77}Se NMR study of nonmagnetic-magnetic transition in (TMTSF){sub 2}X

    Energy Technology Data Exchange (ETDEWEB)

    Mito, T., E-mail: mito_takeshi@hotmail.co [Graduate School of Material Science, University of Hyogo, Hyogo 678-1297 (Japan); Nishiyama, K.; Koyama, T.; Ueda, K.; Kohara, T.; Takeuchi, K.; Akutsu, H.; Yamada, J. [Graduate School of Material Science, University of Hyogo, Hyogo 678-1297 (Japan); Kornilov, A.; Pudalov, V.M. [P.N. Lebedev Physics Institute, Moscow 119991 (Russian Federation); Qualls, J.S. [Sonoma State University, Rohnert Park, CA 94928 (United States)

    2010-12-15

    {sup 77}Se NMR measurements have been carried out on (TMTSF){sub 2}X (X = PF{sub 6} and AsF{sub 6}) single crystals. For both compounds, NMR lines split into double-peaked spectra in the SDW state, which is explained with sinusoidal internal field at Se nucleus positions having the same incommensurate wave number with that of the SDW order. No change in the lineshape was observed at T{sub x} at which the spin-relaxation rate shows a kink, suggesting that this anomaly does not cause significant static changes in internal field at the Se-site.

  5. Dynamic Processes in Prochiral Solvating Agents (pro-CSAs Studied by NMR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jan Labuta

    2014-05-01

    Full Text Available Several dynamic processes, including tautomerism and macrocyclic inversion, in 1H-NMR prochiral solvating agents (pro-CSAs are investigated. Various features of pro-CSA, including modes of interaction for complex formation, stoichiometry, binding strength and temperature effects were compared for three representative pro-CSA molecules. Structural effects of conjugated tetrapyrrole pro-CSA on the mechanism of enantiomeric excess determination are also discussed. Detailed analysis of species (complexes and dynamic processes occurring in solution and their 1H-NMR spectral manifestations at various temperatures is presented.

  6. NMR characteristics of intracellular K in the rat salivary gland: A sup 39 K NMR study using double-quantum filtering

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yoshiteru; Murakami, Masataka; Suzuki, Eiji; Watari, Hiroshi (National Institute for Physiological Sciences, Myodaiji, Okazaki (Japan)); Nagayama, Kuniaki (JEOL ltd., Akishima, Tokyo (Japan))

    1990-01-23

    Intracellular K of the perfused rat mandibular salivary gland was measured by {sup 39}K NMR spectroscopy at 8.45 T. Multiple-quantum NMR arising from multiple-exponential decay was used to eliminate the resonance due to extracellular K in the perfused gland at 25{degree}C. The resonance due to intracellular K consisted of two Lorentzian signals. These results suggest the possibility of the presence of a single homogeneous population of intracellular K with a correlation time of ca. 2.5 {times} 10 {sup {minus}8} s and a quadrupolar coupling constant ca. 1.4 MHz.

  7. Solid-state (13)C NMR and synchrotron SAXS/WAXS studies of uniaxially-oriented polyethylene.

    Science.gov (United States)

    Afeworki, Mobae; Brant, Pat; Lustiger, Arnold; Norman, Alexander

    2015-11-01

    We report solid-state (13)C NMR and synchrotron wide-and small-angle X-ray scattering experiments (WAXS, SAXS) on metallocene linear low density polyethylene films (e.g., Exceed™ 1018 mLLDPE; nominally 1MI, 0.918 density ethylene-hexene metallocene copolymer) as a function of uniaxial draw ratio, λ. Combined, these experiments provide an unambiguous, quantitative molecular view of the orientation of both the crystalline and amorphous phases in the samples as a function of draw. Together with previously reported differential scanning calorimetry (DSC), gas transport measurements, transmission electron microscopy (TEM), optical birefringence, small angle X-ray scattering (SAXS) as well as other characterization techniques, this study of the state of orientation in both phases provides insight concerning the development of unusually high barrier properties of the most oriented samples (λ=10). In this work, static (non-spinning) solid-state NMR measurements indicate that in the drawn Exceed(TM) films both the crystalline and amorphous regions are highly oriented. In particular, chemical shift data show the amorphous phase is comprised increasingly of so-called "taut tie chains" (or tie chains under any state of tautness) in the mLLDPE with increasing draw ratio - the resonance lines associated with the amorphous phase shift to where the crystalline peaks are observed. In the sample with highest total draw (λ=10), virtually all of the chains in the non-crystalline region have responded and aligned in the machine (draw) direction. Both monoclinic and orthorhombic crystalline peaks are observed in high-resolution, solid-state magic-angle spinning (MAS) NMR measurements of the oriented PE films. The orientation is comparable to that obtained for ultra-high molecular weight HDPE fibers described as "ultra-oriented" in the literature. Furthermore, the presence of a monoclinic peak in cold-drawn samples suggests that there is an appreciable internal stress associated

  8. Oligomerization of protegrin-1 in the presence of DPC micelles. A proton high-resolution NMR study.

    Science.gov (United States)

    Roumestand, C; Louis, V; Aumelas, A; Grassy, G; Calas, B; Chavanieu, A

    1998-01-16

    Protegrins are members of a family of five Cys-rich naturally occurring cationic antimicrobial peptides. The NMR solution structure of protegrin-1 (PG-1) has been previously determined as a monomeric beta-hairpin both in water and in dimethylsulfoxide solution. Protegrins are bactericidal peptides but their mechanism of action is still unknown. In order to investigate the structural basis of their cytotoxicity, we studied the effect of lipid micelles on the structure of PG-1. The NMR study reported in the present work indicates that PG-1 adopts a dimeric structure when it binds to dodecylphosphocholine micelles. Moreover, the amide proton exchange study suggests the possibility of an association between several dimers.

  9. Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

    Directory of Open Access Journals (Sweden)

    Mohamed Haouas

    2016-06-01

    Full Text Available The dynamic behavior of tetrapropylammonium (TPA cations in the clear precursor sols for silicalite synthesis has been investigated by 1H diffusion ordered spectroscopy (DOSY, T1, T2, and T1ρ 1H relaxation, as well as 1H→13C cross polarization (CP nuclear magnetic resonance. The DOSY NMR experiments showed the presence of strong solute–solvent interactions in concentrated sols, which are decreasing upon dilution. Similarities in dependence of diffusion coefficients with fractional power of the viscosity constant observed for nanoparticles, TPA cations and water led to the conclusion that they aggregate as anisotropic silicate-TPA particles. Relaxation studies as well as 1H→13C CP experiments provide information on dynamic properties of ethanol, water and TPA cations, which are function of silicate aggregates. The general tendency showed that the presence of silicate as oligomers and particles decreases the relaxation times, in particular T2 and T1ρH, as a consequence of involvement of these latter in ion-pairing interactions with water-solvated TPA molecules slowing down their mobility. Furthermore, from the 1H→13C CP dynamics curve profiles a change in the CP transfer regime was observed from fast (TCH << T1ρH for solutions without silicates to moderate (TCH~T1ρH when silicates are interacting with the TPA cations that may reflect the occlusion of TPA into flexible silicate hydrate aggregates.

  10. Study on optimization of YBCO thin film stack for compact NMR magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.B., E-mail: kim@elec.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan); Kimoto, T. [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushimanaka, Kita-ku, Okayama 700-8530 (Japan); Hahn, S.; Iwasa, Y.; Voccio, J. [Francis Bitter Magnet Laboratory, MIT, Cambridge, MA 02139 (United States); Tomita, M. [Applied Superconductivity Materials Tech. Div., Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji-shi, Tokyo 185-8540 (Japan)

    2013-01-15

    Highlights: ► Stacking methods for compact NMR magnet using YBCO thin films were tested. ► The stacking angles are 0°, 22.5° and 90° against the rolling direction. ► The best spatial field homogeneity was obtained in rotation angle of 22.5°. ► The maximum trapped magnetic fields of 0.4 T was obtained at 77.4 K. ► The maximum trapped magnetic fields of 0.95 T was obtained at 21 K. -- Abstract: A compact high temperature superconducting (HTS) magnet, which consists of a stack of 500 HTS thin film annuli, was constructed and tested. Each thin film annulus, manufactured by the AMSC using the Rolling Assisted Bi-axially Textured Substrate (RABiTS) method, has a square cross-section of 40 mm × 40 mm with a thickness of 80 m. It has a 25-mm center hole created by machining. This paper reports a study on the anisotropic J{sub c} issue due to the rolling procedure of the Ni substrate direction and its impact on field homogeneity. Also, three different stacking methods with rotation angles of 22.5°, 90°, and 0° against the rolling direction have been tested to study their impacts on strength, spatial homogeneity, and temporal stability of trapped fields. Finally, the 500-annulus magnet was tested at 21 K under a cryogen-free environment using a GM cryocooler. The spatial field homogeneity and temporal stability were measured at 21 K and compared with those obtained in a bath of liquid nitrogen at 77 K.

  11. The interaction of small molecules with phospholipid membranes studied by 1H NOESY NMR under magic-angle spinning1

    Institute of Scientific and Technical Information of China (English)

    Holger A SCHEIDT; Daniel HUSTER

    2008-01-01

    The interaction of small molecules with lipid membranes and the exact knowledge of their binding site and bilayer distribution is of great pharmacological impor-tance and represents an active field of current biophysical research. Over the last decade, a highly resolved 1H solid-state NMR method has been developed that allows measuring localization and distribution of small molecules in membranes. The classical solution 1H NMR NOESY technique is applied to lipid membrane samples under magic-angle spinning (MAS) and NOESY cross-relaxation rates are determined quantitatively. These rates are proportional to the contact probability between molecular segments and therefore an ideal tool to study intermolecular interactions in membranes. Here, we review recent 1H MAS NOESY applications that were carried out to study lateral lipid organization in mixed membranes and the interaction of membranes with water, ethanol, small aromatic compounds, peptides, fluorescence labels, and lipophilic nucleosides.

  12. All-atom Molecular Dynamic Simulations and NMR Spectra Study on Intermolecular Interactions of N,N-dimethylacetamide-Water System

    Institute of Scientific and Technical Information of China (English)

    Rong Zhang; Zai-you Tan; San-lai Luo

    2008-01-01

    N,N-dimethylacetamide (DMA) has been investigated extensively in studying models of peptide bonds. An all-atom MD simulation and the NMR spectra were performed to investigate the interactions in the DMA- water system. The radial distribution functions (RDFs) and the hydrogen-bonding network were used in MD simulations. There are strong hydrogen bonds and weak C-H…O contacts in the mixtures, as shown by the analysis of the RDFs. The insight structures in the DMA-water mixtures can be classified into different regions by the analysis of the hydrogen-bonding network. Chemical shifts of the hydrogen atom of water molecule with concentration and temperatures are adopted to study the interactions in the mixtures. The results of NMR spectra show good agreement with the statistical results of hydrogen bonds in MD simulations.

  13. Effect of genetic and phenotypic factors on the composition of commercial marmande type tomatoes studied through HRMAS NMR spectroscopy.

    Science.gov (United States)

    Iglesias, María José; García López, Jesús; Collados Luján, Juan Fernando; López Ortiz, Fernando; Bojórquez Pereznieto, Humberto; Toresano, Fernando; Camacho, Francisco

    2014-01-01

    The effects of genetic, technological and environmental factors on the chemical composition of four marmande type tomato varieties have been investigated. The study is based on the analysis of (1)H HRMAS NMR spectra of tomato purée using a combination of partial least squares (PLS) and assigned signal analysis (ASA). In agreement with genetic, morphological and taste characteristics of the tomatoes studied, the analysis of the NMR data allows two groups of samples to be differentiated. The type of culture and climatic conditions can reduce the compositional differences. The extension of the compositional changes produced by climatic conditions is variety-depend. Neither grafting nor perlite affect significantly the relative content of primary metabolites. This was not the case for tomatoes grown using the pure hydroponic production system based on the recirculation of nutrient solution, New Growing System NGS®, which seems to be an effective agricultural approach to improve tomato quality.

  14. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The synthesis of photochromic 3,3-di( 4 ′ -fluorophenyl-3H-benzopyrans fused to an indole moiety is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data ( λ max⁡ of colored form, colorability, and rate constant of bleaching obtained by UV-visible spectroscopy are reported.

  15. Photochromism of indolino-benzopyrans studied by NMR and UV-visible spectroscopy

    OpenAIRE

    S. Delbaere; J. Berthet; M. A. Salvador; Vermeersch, G.; Oliveira,M. M.

    2006-01-01

    The synthesis of photochromic 3,3-di(4′-fluorophenyl)-3H-benzopyrans fused to an indole moiety is described. The structures of photomerocyanines elucidated by NMR spectroscopy and spectrokinetic data (λmax⁡ of colored form, colorability, and rate constant of bleaching) obtained by UV-visible spectroscopy are reported.

  16. A 19F NMR study of C-I....pi- halogen bonding

    DEFF Research Database (Denmark)

    Hauchecorne, Dieter; vand er Veken, Benjamin J.; Herrebout, Wouter A.

    2011-01-01

    The formation of halogen bonded complexes between toluene-d8 and the perfluoroiodopropanes 1-C3F7I and 2-C3F7I has been investigated using 19F NMR spectroscopy. For both Lewis acids, evidence was found for the formation of a C–I⋯π halogen bonded complex. The complex formed is a 1:1 type. Using...

  17. Use of 1 H NMR to study transport processes in porous biosystems

    NARCIS (Netherlands)

    As, van H.; Lens, P.N.L.

    2001-01-01

    The operation of bioreactors and the metabolism of microorganisms in biofilms or soil/sediment systems are strongly dictated by the transport processes therein. Nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) allow nondestructive and noninvasive quantification and v

  18. Time-domain NMR study of the drying of hemicellulose extracted aspen (Populus tremuloides Michx.)

    Science.gov (United States)

    Thomas Elder; Carl Houtman

    2013-01-01

    The effect of hot water on aspen chips has been evaluated using time-domain low-field nuclear magnetic resonance (NMR) spectroscopy. At moisture contents above fiber saturation point, treated chips exhibit relaxation times of free water longer than for the control. This is consistent with the removal of hemicelluloses given the hydrophilicity of these polysaccharides....

  19. NMR study of 1,4-dihydropyridine derivatives endowed with long alkyl and functionalized chains

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, Margarita; Salfran, Esperanza; Rodriguez, Hortensia; Coro, Julieta, E-mail: msuarez@fq.uh.c [Universidad de La Habana (Cuba). Facultad de Quimica. Lab. de Sintesis Organica; Molero, Dolores; Saez, Elena [Universidad Complutense, Madrid (Spain). CAI-RMN; Martinez-Alvarez, Roberto; Martin, Nazario [Universidad Complutense, Madrid (Spain). Facultad de Quimica. Dept. de Quimica Organica I

    2011-07-01

    The {sup 1}H , {sup 13}C and {sup 15}N NMR spectroscopic data for 1,4-dihydropyridine endowed with long alkyl and functionalized chain on C-3 and C-5, have been fully assigned by combination of one- and two dimensional experiments (DEPT, HMBC, HMQC, COSY, nOe). (author)

  20. Phase Structures of Nascent Polyethylene Powder Studied by Wideline Proton NMR

    Institute of Scientific and Technical Information of China (English)

    YAN,Xiao-Wei; WANG,Jing-Dai; REN,Xiao-Hong; YANG,Yong-Rong; JIANG,Bin-Bo; VODA,Mihai Adrian; BERTMER,Marko; STAFF,Siegfried

    2007-01-01

    The wideline proton NMR spectra of polyethylene powder samples were analyzed in terms of contributions from three components: (1) a rigid part with immobile chains, (2) a soft region with liquid-like character which produces a Lorentzian contribution to the spectrum, and (3) an intermediate region in which the rotation of me-thylene groups about C-C bonds is partially hindered. The relative mass fractions as well as chain mobilities varied greatly among samples produced by different polymerization techniques. The NMR crystallinity agreed well with that estimated by WAXD and was much higher than DSC crystallinity, indicating an inclusion of the contribution from a crystalline-amorphous interphase. The crystalline defects in the rigid part could be significantly affected by processing parameters when employing the same type of polymerization technique. The intermediate region in the NMR spectra was analyzed according to the comparison between bimodal high density polyethylene and corresponding linear unimodal one. It was found that the mass fraction of the NMR interphase could be an indication of the percentage of tie molecules between crystalline lamellae and thus may significantly affect the mechanical properties of polymeric material.

  1. Chiral diamine-silver(I)-alkene complexes: a quantum chemical and NMR study

    DEFF Research Database (Denmark)

    Kieken, Elsa; Wiest, Olaf; Helquist, Paul

    2005-01-01

    The ability of chiral diamine silver complexes to bind chiral and prochiral alkenes has been analyzed in detail. The stereoselectivity in binding of alkenes to a chiral ethanediamine silver complex has been investigated by NMR. The low-energy conformations of several small model complexes have be...

  2. NMR studies of the GTP/GDP binding domain of translation initiation factor IF2

    NARCIS (Netherlands)

    Tishchenko, Evgeny Vladimirovich

    2005-01-01

    Translation Initiation Factor 2 (IF2) plays an important role in the initiation stage of bacterial protein biosynthesis. This protein binds both fMet-tRNA and 30S ribosomal subunit in the presence of GTP, and it stimulates the formation of the 70S initiation complex. The NMR samples of the 15N-, 15N

  3. 1H NMR spectroscopy-based interventional metabolic phenotyping: a cohort study of rheumatoid arthritis patients

    DEFF Research Database (Denmark)

    Lauridsen, Michael Brændgaard; Bliddal, Henning; Christensen, Robin Daniel Kjersgaard;

    2010-01-01

    1H NMR spectroscopy-based metabolic phenotyping was used to identify biomarkers in the plasma of patients with rheumatoid arthritis (RA). Forty-seven patients with RA (23 with active disease at baseline and 24 in remission) and 51 healthy subjects were evaluated during a one-year follow-up with a...

  4. Postprandial metabolomics: A pilot mass spectrometry and NMR study of the human plasma metabolome in response to a challenge meal

    Energy Technology Data Exchange (ETDEWEB)

    Karimpour, Masoumeh; Surowiec, Izabella; Wu, Junfang [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Gouveia-Figueira, Sandra [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå (Sweden); Pinto, Rui [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Bioinformatics Infrastructure for Life Sciences (Sweden); Trygg, Johan [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden); Zivkovic, Angela M. [Department of Nutrition, University of California, Davis, One Shields Ave, CA 95616 (United States); Nording, Malin L., E-mail: malin.nording@umu.se [Computational Life Science Cluster (CLiC), Department of Chemistry, Umeå University, 90187 Umeå (Sweden)

    2016-02-18

    The study of postprandial metabolism is relevant for understanding metabolic diseases and characterizing personal responses to diet. We combined three analytical platforms – gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) – to validate a multi-platform approach for characterizing individual variation in the postprandial state. We analyzed the postprandial plasma metabolome by introducing, at three occasions, meal challenges on a usual diet, and 1.5 years later, on a modified background diet. The postprandial response was stable over time and largely independent of the background diet as revealed by all three analytical platforms. Coverage of the metabolome between NMR and GC-MS included more polar metabolites detectable only by NMR and more hydrophobic compounds detected by GC-MS. The variability across three separate testing occasions among the identified metabolites was in the range of 1.1–86% for GC-MS and 0.9–42% for NMR in the fasting state at baseline. For the LC-MS analysis, the coefficients of variation of the detected compounds in the fasting state at baseline were in the range of 2–97% for the positive and 4–69% for the negative mode. Multivariate analysis (MVA) of metabolites detected with GC-MS revealed that for both background diets, levels of postprandial amino acids and sugars increased whereas those of fatty acids decreased at 0.5 h after the meal was consumed, reflecting the expected response to the challenge meal. MVA of NMR data revealed increasing postprandial levels of amino acids and other organic acids together with decreasing levels of acetoacetate and 3-hydroxybutanoic acid, also independent of the background diet. Together these data show that the postprandial response to the same challenge meal was stable even though it was tested 1.5 years apart, and that it was largely independent of background diet. This work demonstrates the efficacy of a

  5. Study of multi-site chemical exchange in solution state by NMR: 1D experiments with multiply selective excitation

    Indian Academy of Sciences (India)

    Samanwita Pal

    2010-07-01

    Chemical exchange in solution state has been investigated traditionally by both 1D and 2D NMR, permitting the extraction of kinetic parameters (e.g. the spin-lattice relaxation time 1, the exchange rate constant and the activation parameters). This work demonstrates a simple 1D NMR approach employing multiply selective excitation to study multi-site exchange processes in solution, applying it to systems that exhibit three-site exchange. This approach involves simultaneous excitation of all - or a chosen subset of - the exchanging sites by using an appropriately modulated shaped radiofrequency pulse. The pulse sequence, as well as analysis is summarized. Significant features of the experiment, which relies on sign labelling of the exchanging sites, include considerably shorter experiment time compared to standard 2D exchange work, clear definition of the exchange time window and uniform pulse non-ideality effects for all the exchanging sites. Complete kinetic information is reported in the study of dynamic processes in superacid solutions of two weak bases, studied by 1H NMR. An analytical solution, leading to the determination of four rate parameters, is presented for proton exchange studies on these systems, which involve a mixture of two weak bases in arbitrary concentration ratio, and stoichiometric excess of the superacid.

  6. Impact of the composition of polysaccharide composite gels on small molecules diffusion: A rheological and NMR study

    OpenAIRE

    2010-01-01

    The gelation mechanism of carrageenan depends on the amount and nature of the polysaccharide, and is cation sensitive. From a rheological approach, this specificity leads to different textural properties. In composite gels with carrageenans, starch and sucrose, the presence of κ/κ2-carrageenan, even at low levels, has an impact on textural and structural properties. In this study, rheological and diffusion NMR measurements were performed on composite gels to probe gel structure at the macro- ...

  7. Characterizing crystal disorder of trospium chloride: a comprehensive,(13) C CP/MAS NMR, DSC, FTIR, and XRPD study.

    Science.gov (United States)

    Urbanova, Martina; Sturcova, Adriana; Brus, Jiri; Benes, Hynek; Skorepova, Eliska; Kratochvil, Bohumil; Cejka, Jan; Sedenkova, Ivana; Kobera, Libor; Policianova, Olivia; Sturc, Antonin

    2013-04-01

    Analysis of C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and X-ray powder diffraction data of trospium chloride (TCl) products crystallized from different mixtures of water-ethanol [φ(EtOH) = 0.5-1.0] at various temperatures (0°C, 20°C) and initial concentrations (saturated solution, 30%-50% excess of solvent) revealed extensive structural variability of TCl. Although (13) C CP/MAS NMR spectra indicated broad variety of structural phases arising from molecular disorder, temperature-modulated DSC identified presence of two distinct components in the products. FTIR spectra revealed alterations in the hydrogen bonding network (ionic hydrogen bond formation), whereas the X-ray diffraction reflected unchanged unit cell parameters. These results were explained by a two-component character of TCl products in which a dominant polymorphic form is accompanied by partly separated nanocrystalline domains of a secondary phase that does not provide clear Bragg reflections. These phases slightly differ in the degree of molecular disorder, in the quality of crystal lattice and hydrogen bonding network. It is also demonstrated that, for the quality control of such complex products, (13) C CP/MAS NMR spectroscopy combined with factor analysis (FA) can satisfactorily be used for categorizing the individual samples: FA of (13) C CP/MAS NMR spectra found clear relationships between the extent of molecular disorder and crystallization conditions. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1235-1248, 2013.

  8. MAS-NMR study of lithium zinc silicate glasses and glass-ceramics with various ZnO content

    Science.gov (United States)

    Goswami, Madhumita; Kothiyal, Govind P.; Montagne, Lionel; Delevoye, Laurent

    2008-02-01

    Lithium zinc silicate glasses of composition (mol%): 17.5Li 2O-(72- x)SiO 2- xZnO-5.1Na 2O-1.3P 2O 5-4.1B 2O 3, 5.5⩽ x⩽17.7, were prepared by conventional melt-quenched technique and converted to glass-ceramic by controlled crystallization process. 29Si and 31P MAS-NMR was used to characterize the structure of both glass and glass-ceramic samples. Despite the complex glass composition, Q2, Q3 and Q4 sites are identified from 29Si MAS-NMR, which relative intensities are found to vary with the ZnO content, indicating a network depolymerization by ZnO. Moreover, well separated Q3 and Q4 resonances for low ZnO content indicates the occurrence of phase separation. From 31P MAS-NMR, it is seen that phosphorus is mainly present in the form of ortho-( Q0) and pyro-phosphate ( Q1) structural units and variation of ZnO content did not have much effect on these resonances, which provides an additional evidence for phase separation in the glass. On conversion to glass-ceramics, lithium disilicate (Li 2Si 2O 5), lithium zinc ortho-silicate (Li 3Zn 0.5SiO 4), tridymite (SiO 2) and cristobalite (SiO 2) were identified as major silicate crystalline phases. Using 29Si MAS-NMR, quantification of these silicate crystalline phases is carried out and correlated with the ZnO content in the glass-ceramics samples. In addition, 31P spectra unambiguously revealed the presence of crystalline Li 3PO 4 and (Na,Li) 3PO 4 in the glass-ceramics.

  9. 13C CP/MAS NMR and DFT studies of thiazides

    Science.gov (United States)

    Latosińska, J. N.

    2003-02-01

    The 13C MAS solid state NMR spectra of four sulphonamide derivatives of 1,2,4-benzothiadiazine-1,1-dioxides, commonly known as thiazides, were recorded and the chemical shifts and chemical shift anisotropy (CSA) were measured. Analysis of the experimental 13C shielding parameters was supported by DFT theoretical calculations carried out within the gauge-including atomic orbital (GIAO), semiempirical Typed Neglect of Differential Overlap (TNDO/2) approach and by the spectra estimations performed by ChemNMR Pro 6.0, ACD-I/LAB, SpecInfo and gNMR. It was found that the chemical shifts obtained with ChemNMR Pro 6.0, ACD-I/LAB, SpecInfo and gNMR were insensitive to the substitution effects, whereas the semiempirical TNDO/2 and density functional theory (DFT) B3LYP/6-311+G(2d,p) methods allowed estimation of the influence of substituents on the chemical shielding and consequently, the chemical shift. The influence of the substituents at C3 position of the ring on the chemical shifts was analysed on the basis of the experimental data and results of the DFT calculations. The values of the chemical shifts and the low values of the anisotropy parameter for the C3 atom in HCTZ, TCTZ and ATZ, strongly indicated that three thiazides HCTZ, TCTZ and ATZ occurred in the form of HCTZ type with the C3 carbon atom participating in a single bond. The following ordering of the substituents according to the increasing electron accepting properties was found: -H<-CH 2SCH 2CHCH 2<-CHCl 2. A detailed analysis of the inductive and coupling effects was made on the basis of 13C chemical shifts and chemical shielding tensor asymmetry parameters on the C3 and C6 carbon atoms.

  10. Autocomplete as Research Tool: A Study on Providing Search Suggestions

    Directory of Open Access Journals (Sweden)

    David Ward

    2012-12-01

    Full Text Available As the library website and on its online searching tools become the primary “branch” many users visit for their research, methods for providing automated, context-sensitive research assistance need to be developed to guide unmediated searching towards the most relevant results.  This study examines one such method, the use of autocompletion in search interfaces, by conducting usability tests on its use in typical academic research scenarios.  The study reports notable findings on user preference for autocomplete features, and suggests best practices for their implementation.

  11. NMr studies of the AMP binding site and mechanism of adenylate kinase

    Energy Technology Data Exchange (ETDEWEB)

    Kuby, S.A.; Fry, D.C.; Mildvan, A.S.

    1986-05-01

    The authors recently located by NMR the MgATP binding site on adenylate kinase correcting the proposed location for this site based on X-ray studies of the binding of salicylate. To determine the conformation and location of the other substrate, they have determined distances from Cr/sup 3 +/ AMPPCP to 6 protons and to the phosphorus atom of AMP on adenylate kinase using the paramagnetic-probe-T/sub 1/ method. They have also used time-dependent NOEs to measure five interproton distances on AMP, permitting evaluation of the conformation of enzyme-bound AMP and its position with respect to metal-ATP. Enzyme-bound AMP exhibits a high-anti glycosyl torsional angle (X = 110/sup 0/), a 3'-endo sugar pucker (delta = 105/sup 0/), and a gauche-trans orientation about the C/sub 4/'-C/sub 5/' bond (..gamma.. = 180/sup 0/). The distance from Cr/sup 3 +/ to the phosphorus of AMP is 6.4 +/- 0.3 A, indicating a reaction coordinate distance of greater than or equal to A which is consistent with an associative SN2 mechanism for the phosphoryl transfer. Ten intermolecular NOEs, from protons of the enzyme to those of AMP were detected. These constraints, together with the conformation of AMP and the X-ray structure of the enzyme, suggest proximity (less than or equal to A) of AMP to leu 116, arg 171, val 173, gln 185, thr 188, and asp 191.

  12. Magic angle spinning NMR of paramagnetic proteins.

    Science.gov (United States)

    Knight, Michael J; Felli, Isabella C; Pierattelli, Roberta; Emsley, Lyndon; Pintacuda, Guido

    2013-09-17

    Metal ions are ubiquitous in biochemical and cellular processes. Since many metal ions are paramagnetic due to the presence of unpaired electrons, paramagnetic molecules are an important class of targets for research in structural biology and related fields. Today, NMR spectroscopy plays a central role in the investigation of the structure and chemical properties of paramagnetic metalloproteins, linking the observed paramagnetic phenomena directly to electronic and molecular structure. A major step forward in the study of proteins by solid-state NMR came with the advent of ultrafast magic angle spinning (MAS) and the ability to use (1)H detection. Combined, these techniques have allowed investigators to observe nuclei that previously were invisible in highly paramagnetic metalloproteins. In addition, these techniques have enabled quantitative site-specific measurement of a variety of long-range paramagnetic effects. Instead of limiting solid-state NMR studies of biological systems, paramagnetism provides an information-rich phenomenon that can be exploited in these studies. This Account emphasizes state-of-the-art methods and applications of solid-state NMR in paramagnetic systems in biological chemistry. In particular, we discuss the use of ultrafast MAS and (1)H-detection in perdeuterated paramagnetic metalloproteins. Current methodology allows us to determine the structure and dynamics of metalloenzymes, and, as an example, we describe solid-state NMR studies of microcrystalline superoxide dismutase, a 32 kDa dimer. Data were acquired with remarkably short times, and these experiments required only a few milligrams of sample.

  13. Arresting Consecutive Steps of a Photochromic Reaction: Studies of β-Thioxoketones Combining Laser Photolysis with NMR Detection

    DEFF Research Database (Denmark)

    Pietrzak, Mariusz; Dobkowski, Jacek; Gorski, Alexandr

    2014-01-01

    Photochromism of monothiodibenzoylmethane has been studied in a number of environments at different temperatures. Direct laser irradiation of a sample located in the NMR magnet allowed in situ monitoring of the phototransformation products, determining their structure, and measuring the kinetics...... of the photochromism in β-thioxoketones. At low temperature in rigid matrices the electronic excitation leads to the formation of the –SH exorotamer of the (Z)-enethiol tautomer. In solutions, further steps are possible, producing a mixture of two other non-chelated enethiol forms. Photoconversion efficiency strongly...... depends on the excitation wavelength. Analysis of the mechanisms of the photochromic processes indicates a state-specific precursor: chelated thione–enol form in the excited S2(ππ*) electronic state. The results show the potential of using laser photolysis coupled with NMR detection for the identification...

  14. XRD, NMR, and EPR study of polycrystalline micro- and nano-diamonds prepared by a shock wave compression method

    Energy Technology Data Exchange (ETDEWEB)

    Shames, Alexander I.; Panich, Alexander M. [Department of Physics, Ben-Gurion University of the Negev, Be' er Sheva (Israel); Mogilyansky, Dmitry [Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Be' er-Sheva (Israel); Sergeev, Nikolay A.; Olszewski, Marcin [Institute of Physics, University of Szczecin (Poland); Boudou, Jean-Paul [Laboratoire Aime Cotton, CNRS, Universite Paris-Sud et ENS Cachan, Orsay (France); Osipov, Vladimir Yu. [Ioffe Physical-Technical Institute, St. Petersburg (Russian Federation)

    2015-11-15

    We report on XRD, NMR, and EPR study of commercial micro- and nano-diamonds of the SSX series fabricated by a shock wave compression method. XRD data analysis shows that SSX samples consist of nanometer cubic diamond domains intermixing with stacking faults and twins. We show that as-received samples reveal a graphitic component, which may be removed by additional purification. Crushing the initial microdiamond powder into submicron and nanometer sizes does not result in noticeable variations of the XRD, NMR, and EPR parameters. This finding is explained by the fact that SSX diamonds are polycrystalline aggregates consisting of numerous nanocrystallites of ∝20-25 nm in size. Therefore, soft crushing of these aggregates diminishes their size, but leaves constituting nanocrystallites and their intrinsically facet surfaces mainly untreated. With that some modification of the outer nanocrystallite surface on crushing is observed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Application of a Pyroprobe-Deuterium NMR System: Deuterium Tracing and Mechanistic Study of Upgrading Process for Lignin Model Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ben, Haoxi; Jarvis, Mark W.; Nimlos, Mark R.; Gjersing, Erica L.; Sturgeon, Matthew R.; Foust, Thomas D.; Ragauskas, Arthur J.; Biddy, Mary J.

    2016-04-21

    In this study, a pyroprobe-deuterium (2H) NMR system has been used to identify isotopomer products formed during the deuteration and ring opening of lignin model compounds. Several common model compounds for lignin and its upgraded products, including guaiacol, syringol, toluene, p-xylene, phenol, catechol, cyclohexane, methylcyclohexane, and methylcyclopentane, have been examined for selective ring opening. Similar pathways for upgrading of toluene and p-xylene has been found, which will undergo hydrogenation, methyl group elimination, and ring opening process, and benzene, cyclohexane, and methylcyclohexane have been found as major intermediates before ring opening. Very interestingly, the 2H NMR analysis for the deuterium-traced ring opening of catechol on Ir/..gamma..-Al2O3 is almost identical to the ring opening process for phenol. The ring opening processes for guaiacol and syringol appeared to be very complicated, as expected. Benzene, phenol, toluene, cyclohexane, and methylcyclohexane have been determined to be the major products.

  16. NMR studies of recombinant Coprinus peroxidase and three site-directed mutants. Implications for peroxidase substrate binding.

    Science.gov (United States)

    Veitch, N C; Tams, J W; Vind, J; Dalbøge, H; Welinder, K G

    1994-06-15

    Proton nuclear magnetic resonance spectroscopy has been used to characterise and compare wild-type fungal and recombinant Coprinus cinereus peroxidase (CIP) and three mutants in which Gly156 and/or Asn157 was replaced by Phe. Analysis of one- and two-dimensional NMR spectra of recombinant CIP was undertaken for comparison with the fungal enzyme and in order to establish a meaningful basis for solution studies of CIP mutants. Proton resonance assignments of haem and haem-linked residues obtained for the cyanide-ligated form of recombinant CIP revealed a high degree of spectral similarity with those of lignin and manganese-dependent peroxidases and extend previously reported NMR data for fungal CIP. The three mutants examined by NMR spectroscopy comprised site-specific substitutions made to a region of the structure believed to form part of the peroxidase haem group access channel for substrate and ligand molecules. Proton resonances of the aromatic side-chains of Phe156 and Phe157 were found to have similar spectral characteristics to those of two phenylalanine residues known to be involved in the binding of aromatic donor molecules to the plant peroxidase, horseradish peroxidase isoenzyme C. The results are discussed in the context of complementary reactivity studies on the mutants in order to develop a more detailed understanding of aromatic donor molecule binding to fungal and plant peroxidases.

  17. Effective factors in providing holistic care: A qualitative study

    Directory of Open Access Journals (Sweden)

    Vahid Zamanzadeh

    2015-01-01

    Full Text Available Background: Holistic care is a comprehensive model of caring. Previous studies have shown that most nurses do not apply this method. Examining the effective factors in nurses′ provision of holistic care can help with enhancing it. Studying these factors from the point of view of nurses will generate real and meaningful concepts and can help to extend this method of caring. Materials and Methods: A qualitative study was used to identify effective factors in holistic care provision. Data gathered by interviewing 14 nurses from university hospitals in Iran were analyzed with a conventional qualitative content analysis method and by using MAXQDA (professional software for qualitative and mixed methods data analysis software. Results: Analysis of data revealed three main themes as effective factors in providing holistic care: The structure of educational system, professional environment, and personality traits. Conclusion: Establishing appropriate educational, management systems, and promoting religiousness and encouragement will induce nurses to provide holistic care and ultimately improve the quality of their caring.

  18. A study on consumer switching behaviour in cellular service provider

    OpenAIRE

    M. Sathish; K.J.Naveen; V.Jeevanantham

    2011-01-01

    Indian mobile market is a fastest growing market and is forecasted to reach 868.47 million users by 2013. India has seen rapid increase in number of players which caused the tariff rates to hit an all time low. This allowed the players to target the low income population increasing the market share. The availability of number of subscriber options for consumers and varied tariff rates of each player, lead the consumers to switch the service providers. The objectives of the study are to find t...

  19. N-15 NMR study of the immobilization of 2,4- and 2,6-dinitrotoluene in aerobic compost

    Science.gov (United States)

    Thorn, K.A.; Pennington, J.C.; Kennedy, K.R.; Cox, L.G.; Hayes, C.A.; Porter, B.E.

    2008-01-01

    Large-scale aerobic windrow composting has been used to bioremediate washout lagoon soils contaminated with the explosives TNT (2,4,6- trinitrotoluene) and RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) at several sites within the United States. We previously used 15N NMR to investigate the reduction and binding of T15NT in aerobic bench -scale reactors simulating the conditions of windrow composting. These studies have been extended to 2,4-dinitrotoluene (2,4DNT) and 2,6-dinitrotoluene (2,6DNT), which, as impurities in TNT, are usually present wherever soils have been contaminated with TNT. Liquid-state 15N NMR analyses of laboratory reactions between 4-methyl-3-nitroaniline-15N, the major monoamine reduction product of 2,4DNT, and the Elliot soil humic acid, both in the presence and absence of horseradish peroxidase, indicated that the amine underwent covalent binding with quinone and other carbonyl groups in the soil humic acid to form both heterocyclic and non-heterocyclic condensation products. Liquid-state 15N NMR analyses of the methanol extracts of 20 day aerobic bench-scale composts of 2,4-di-15N-nitrotoluene and 2,6-di-15N-nitrotoluene revealed the presence of nitrite and monoamine, but not diamine, reduction products, indicating the occurrence of both dioxygenase enzyme and reductive degradation pathways. Solid-state CP/MAS 15N NMR analyses of the whole composts, however, suggested that reduction to monoamines followed by covalent binding of the amines to organic matter was the predominant pathway. ?? 2008 American Chemical Society.

  20. Changes in Porcine Muscle Water Characteristics during Growth—An in Vitro Low-Field NMR Relaxation Study

    Science.gov (United States)

    Bertram, Hanne Christine; Rasmussen, Marianne; Busk, Hans; Oksbjerg, Niels; Karlsson, Anders Hans; Andersen, Henrik Jørgen

    2002-08-01

    This study investigates the effects of developmental stage and muscle type on the mobility and distribution of water within skeletal muscles, using low-field 1H-NMR transverse relaxation measurements in vitro on four different porcine muscles ( M. longissimus dorsi, M. semitendinosus, M. biceps femoris, M. vastus intermedius) from a total of 48 pigs slaughtered at various weight classes between 25 kg and 150 kg. Principal component analysis (PCA) revealed effects of both slaughter weight and muscle type on the transverse relaxation decay. Independent of developmental stage and muscle type, distributed exponential analysis of the NMR T 2 relaxation data imparted the existence of three distinct water populations, T 2b, T 21, and T 22, with relaxation times of approximately 1-10, 45-120, and 200-500 ms, respectively. The most profound change during muscle growth was a shift toward faster relaxation in the intermediate time constant, T 21. It decreased by approx. 24% in all four muscle types during the period from 25 to 150 kg live weight. Determination of dry matter, fat, and protein content in the muscles showed that the changes in relaxation time of the intermediate time constant, T 21, during growth should be ascribed mainly to a change in protein content, as the protein content explained 77% of the variation in the T 21 time constant. Partial least squares (PLS) regression revealed validated correlations in the region of 0.58 to 0.77 between NMR transverse relaxation data and muscle development for all the four muscle types, which indicates that NMR relaxation measurements may be used in the prediction of muscle developmental stage.

  1. NMR GHZ

    CERN Document Server

    Laflamme, R; Zurek, W H; Catasti, P; Mariappan, S V S

    1998-01-01

    We describe the creation of a Greenberger-Horne-Zeilinger (GHZ) state of the form |000>+|111> (three maximally entangled quantum bits) using Nuclear Magnetic Resonance (NMR). We have successfully carried out the experiment using the proton and carbon spins of trichloroethylene, and confirmed the result using state tomography. We have thus extended the space of entangled quantum states explored systematically to three quantum bits, an essential step for quantum computation.

  2. Unscrambling micro-solvation of -COOH and -NH groups in neat dimethyl sulfoxide: insights from (1)H-NMR spectroscopy and computational studies.

    Science.gov (United States)

    Takis, Panteleimon G; Papavasileiou, Konstantinos D; Peristeras, Loukas D; Boulougouris, Georgios C; Melissas, Vasilios S; Troganis, Anastassios N

    2017-05-31

    Dimethyl sulfoxide (DMSO) has a significant, multi-faceted role in medicine, pharmacy, and biology as well as in biophysical chemistry and catalysis. Its physical properties and impact on biomolecular structures still attract major scientific interest, especially the interactions of DMSO with biomolecular functional groups. In the present study, we shed light on the "isolated" carboxylic (-COOH) and amide (-NH) interactions in neat DMSO via(1)H NMR studies along with extensive theoretical approaches, i.e. molecular dynamics (MD) simulations, density functional theory (DFT), and ab initio calculations, applied on model compounds (i.e. acetic and benzoic acid, ethyl acetamidocyanoacetate). Both experimental and theoretical results show excellent agreement, thereby permitting the calculation of the association constants between the studied compounds and DMSO molecules. Our coupled MD simulations, DFT and ab initio calculations, and NMR spectroscopy results indicated that complex formation is entropically driven and DMSO molecules undergo multiple strong interactions with the studied molecules, particularly with the -COOH groups. The combined experimental and theoretical techniques unraveled the interactions of DMSO with the most abundant functional groups of peptides (i.e. peptide bonds, side chain and terminal carboxyl groups) in high detail, providing significant insights on the underlying thermodynamics driving these interactions. Moreover, the developed methodology for the analysis of the simulation results could serve as a template for future thermodynamic and kinetic studies of similar systems.

  3. Preparation of Pt-Tl clusters showing new geometries. X-ray, NMR and luminescence studies.

    Science.gov (United States)

    Belío, Úrsula; Fuertes, Sara; Martín, Antonio

    2014-07-28

    Square planar complexes [Pt(CNC)L] (CNC = C,N,C-2,6-NC5H3(C6H4-2)2; L = tht (tetrahydrothiophene, SC4H8, 1), L = CN(t)Bu (2)) react with TlPF6 in different Pt/Tl molar ratios (3/1 in the case of 1 and 1/1 in the case of 2) yielding the complexes [{Pt(CNC)(tht)}3Tl](PF6) (3) and [Pt(CNC)(CN(t)Bu)Tl](PF6) (4), respectively. The structures of 3 and 4 (X-ray) show the presence of Pt→Tl dative bonds unsupported by any bridging ligands. In complex 3, the only Tl centre is simultaneously bonded to three Pt atoms forming a perfect equilateral triangle with Pt-Tl distances of 2.9088(5) Å, remarkably short. Complex 4 is formed by three "Pt(CNC)(CN(t)Bu)Tl" units, disposed in a triangular fashion, linked together through η(6)-Tl-arene interactions, and showing Pt-Tl bonds with distances of ca. 3.04 Å. The study of these crystal structures would seem to indicate that the difference between the Pt/Tl ratios found in the complexes 3 and 4 is due to the steric requirements of the L ligand bonded to Pt. NMR studies both in solution and in the solid state show that the Pt-Tl bond persists in solutions of 3 and 4. The UV-vis spectra of 3 and 4 in solution display the same profiles as those of 1 and 2, which may suggest a partial dissociation of the Pt-Tl bond in solution. However, by DFT calculations it was proved that in this case the formation of the Pt-Tl dative bond does not produce the expected blue-shift in the UV-vis absorptions. The emissive behaviour of 1-4 in the solid state and in frozen solutions is also studied and included in this work.

  4. 1H NMR and Rheological Studies of the Calcium Induced Gelation Process in Aqueous Low Methoxyl Pectin Solutions

    Science.gov (United States)

    Dobies, M.; Kuśmia, S.; Jurga, S.

    2006-07-01

    The 1H NMR relaxometry in combination with water proton spin-spin relaxation time measurements and rheometry have been applied to study the ionic gelation of 1% w/w aqueous low methoxyl pectin solution induced by divalent Ca2+ cations from a calcium chloride solution. The model-free approach to the analysis of 1H NMR relaxometry data has been used to separate the information on the static (β) and dynamic () behaviour of the systems tested. The 1H NMR results confirm that the average mobility of both water and the pectin molecules is largely dependent on the concentration of the cross-linking agent. The character of this dependency (β, and T2 vs. CaCl2 concentration) is consistent with the two-stage gelation process of low methoxyl pectin, in which the formation of strongly linked dimer associations (in the range of 0-2.5 mM CaCl2) is followed by the appearance of weak inter-dimer aggregations (for CaCl2≥ 3.5 mM). The presence of the weak gel structure for the sample with 3.5 mM CaCl2 has been confirmed by rheological measurements. Apart from that, the T1 and T2 relaxation times have been found to be highly sensitive to the syneresis phenomenon, which can be useful to monitor the low methoxyl pectin gel network stability.

  5. Evidence for DAPI intercalation in CG sites of DNA oligomer [d(CGACGTCG)]2: a 1H NMR study.

    Science.gov (United States)

    Trotta, E; D'Ambrosio, E; Ravagnan, G; Paci, M

    1995-01-01

    The interaction between 4',6-diamidino-2-phenylindole (DAPI) and the DNA oligomer [d(CGACGTCG)]2 has been investigated by proton one- and two-dimensional NMR spectroscopy in solution. Compared with the minor groove binding of the drug to [d(GCGATCGC)]2, previously studied by NMR spectroscopy, the interaction of DAPI with [d(CGACGTCG)]2 appears markedly different and gives results typical of a binding mechanism by intercalation. C:G imino proton signals of the [d(CGACGTCG)]2 oligomer as well as DAPI resonances appear strongly upfield shifted and sequential dipolar connectivities between cytosine and guanine residues show a clear decrease upon binding. Moreover, protons lying in both the minor and major grooves of the DNA double helix appear involved in the interaction, as evidenced principally by intermolecular drug-DNA NOEs. In particular, the results indicate the existence of two stereochemically non-equivalent intercalation binding sites located in the central and terminal adjacent C:G base pairs of the palindromic DNA sequence. Different lifetimes of the complexes were also observed for the two sites of binding. Moreover, due to the fast exchange on the NMR timescale between free and bound species, different interactions in dynamic equilibrium with the observed intercalative bindings were not excluded. PMID:7753623

  6. Quantum-chemical, NMR, FT IR, and ESI MS studies of complexes of colchicine with Zn(II).

    Science.gov (United States)

    Jankowski, Wojciech; Kurek, Joanna; Barczyński, Piotr; Hoffmann, Marcin

    2017-04-01

    Colchicine is a tropolone alkaloid from Colchicinum autumnale. It shows antifibrotic, antimitotic, and anti-inflammatory activities, and is used to treat gout and Mediterranean fever. In this work, complexes of colchicine with zinc(II) nitrate were synthesized and investigated using DFT, (1)H and (13)C NMR, FT IR, and ESI MS. The counterpoise-corrected and uncorrected interaction energies of these complexes were calculated. We also calculated their (1)H, (13)C NMR, and IR spectra and compared them with the corresponding experimentally obtained data. According to the ESI MS mass spectra, colchicine forms stable complexes with zinc(II) nitrate that have various stoichiometries: 2:1, 1:1:1, and 2:1:1 with respect to colchichine, Zn(II), and nitrate ion. All of the complexes were investigated using the quantum theory of atoms in molecules (QTAIM). The calculated and the measured spectra showed differences before and after the complexation process. Calculated electron densities and bond critical points indicated the presence of bonds between the ligands and the central cation in the investigated complexes that satisfied the quantum theory of atoms in molecules. Graphical Abstract DFT, NMR, FT IR, ESI MS, QTAIM and puckering studies of complexes of colchicine with Zn(II).

  7. Two-dimensional NMR relaxometry study of pore space characteristics of carbonate rocks from a Permian aquifer

    Science.gov (United States)

    Schoenfelder, Wiete; Gläser, Hans-Reinhard; Mitreiter, Ivonne; Stallmach, Frank

    2008-06-01

    Limestones and karstified limestones (dolostones) from a Permian aquifer in Central Germany were studied by 1H 2D NMR relaxometry and PFG NMR diffusometry, aiming at a non-destructive characterization of the pore space. Information concerning pore size distribution and water diffusion were in accord for different samples of each type of rock, but differed fundamentally between limestones and dolostones. The results of the 2D relaxometry measurements revealed a ratio of surface relaxation times Ts1/ Ts2 of about 2 for the limestones and about 4.5 for the dolostones, mirroring the different content of iron and manganese in the solid pore walls. In consideration of thin section interpretation, the corresponding fraction in the T1- T2 relaxation time distributions was attributed to interparticle porosity. Porosity of large vugs is clearly displayed by relaxation times longer than 1 s in the dolostones only. A third fraction of the total water-saturated pore space in the dolostones, which is clearly displayed in the 2D relaxation time distributions at the smallest relaxation times and a Ts1/ Ts2 ratio of about 12, is attributed to intrafossil porosity. The porosity classification, basing on non-destructive NMR experiments, is verified by mercury intrusion porosimetry and thin section interpretation.

  8. Predicting ESR Peaks in Copper (II Chelates Having Quadrupolar Coordinating Sites by NMR, ESR and NQR Techniques: A DFT Study

    Directory of Open Access Journals (Sweden)

    Harminder Singh

    2015-06-01

    Full Text Available Computational chemistry was helpful in predicting the number of ESR peaks in Cu (II complexes having a large number of spatially different NMR and ESR active nuclei. The presence of the large Jahn-Teller effect and the high value of spin-orbit coupling constant of the metal ion made the experimental determination of the exact number of ESR peaks quite difficult in such complexes. Fourteen distorted poly-dentate chelating Cu(II complexes included in this study were of two types such as [Cu(gly2] , [Cu(edta]4-,[Cu(tpyX2] (X= Cl, Br, I, NCS and [Cu(en2]2+, [Cu(teta]2+, Cu(tepa]2+ ,[Cu(peha]2+, [Cu(detaX2] (X= Cl, Br, I, NCS.The latter eight complexes belonged to an important class of ligands called polyethylene polyamines. Density functional theory implemented in ADF: 2010.02 was applied. Three parameters of both the ESR (A ten and NQR (NQCC, for the Cu(II and the coordinating atoms of the ligands were obtained from “ESR/EPR program” and two NMR parameters namely the shielding constants (σ and chemical shifts (δ were obtained from “NMR/EPR program” after optimization of the complexes. The species having the same values of these 5 parameters were expected to be spatially equivalent to undergo the same hyperfine interaction with Cu (II.

  9. NMR-based metabolomics and breath studies show lipid and protein catabolism during low dose chronic T(1)AM treatment.

    Science.gov (United States)

    Haviland, J A; Reiland, H; Butz, D E; Tonelli, M; Porter, W P; Zucchi, R; Scanlan, T S; Chiellini, G; Assadi-Porter, F M

    2013-12-01

    3-Iodothyronamine (T1 AM), an analog of thyroid hormone, is a recently discovered fast-acting endogenous metabolite. Single high-dose treatments of T1 AM have produced rapid short-term effects, including a reduction of body temperature, bradycardia, and hyperglycemia in mice. The effect of daily low doses of T1 AM (10 mg/kg) for 8 days on weight loss and metabolism in spontaneously overweight mice was monitored. The experiments were repeated twice (n = 4). Nuclear magnetic resonance (NMR) spectroscopy of plasma and real-time analysis of exhaled (13) CO2 in breath by cavity ring down spectroscopy (CRDS) were used to detect T1 AM-induced lipolysis. CRDS detected increased lipolysis in breath shortly after T1 AM administration that was associated with a significant weight loss but independent of food consumption. NMR spectroscopy revealed alterations in key metabolites in serum: valine, glycine, and 3-hydroxybutyrate, suggesting that the subchronic effects of T1 AM include both lipolysis and protein breakdown. After discontinuation of T1 AM treatment, mice regained only 1.8% of the lost weight in the following 2 weeks, indicating lasting effects of T1 AM on weight maintenance. CRDS in combination with NMR and (13) C-metabolic tracing constitute a powerful method of investigation in obesity studies for identifying in vivo biochemical pathway shifts and unanticipated debilitating side effects. Copyright © 2013 The Obesity Society.

  10. NMR study comparing capillary trapping in Berea sandstone of air, carbon dioxide, and supercritical carbon dioxide after imbibition of water

    Science.gov (United States)

    Prather, Cody A.; Bray, Joshua M.; Seymour, Joseph D.; Codd, Sarah L.

    2016-02-01

    Nuclear magnetic resonance (NMR) techniques were used to study the capillary trapping mechanisms relevant to carbon sequestration. Capillary trapping is an important mechanism in the initial trapping of supercritical CO2 in the pore structures of deep underground rock formations during the sequestration process. Capillary trapping is considered the most promising trapping option for carbon sequestration. NMR techniques noninvasively monitor the drainage and imbibition of air, CO2, and supercritical CO2 with DI H2O at low capillary numbers in a Berea sandstone rock core under conditions representative of a deep underground saline aquifer. Supercritical CO2 was found to have a lower residual nonwetting (NW) phase saturation than that of air and CO2. Supercritical CO2 behaves differently than gas phase air or CO2 and leads to a reduction in capillary trapping. NMR relaxometry data suggest that the NW phase, i.e., air, CO2, or supercritical CO2, is preferentially trapped in larger pores. This is consistent with snap-off conditions being more favorable in macroscale pores, as NW fluids minimize their contact area with the solid and hence prefer larger pores.

  11. Interaction of Cu(II and Ni(II with Ypk9 Protein Fragment via NMR Studies

    Directory of Open Access Journals (Sweden)

    Massimiliano Francesco Peana

    2014-01-01

    Full Text Available P1D2E3K4H5E6L7 (PK9-H, a fragment of Ypk9, the yeast homologue of the human Park9 protein, was studied for its coordination abilities towards Ni(II and Cu(II ions through mono- and bi-dimensional NMR techniques. Both proteins are involved in the transportation of metal ions, including manganese and nickel, from the cytosol to the lysosomal lumen. Ypk9 showed manganese detoxification role, preventing a Mn-induced Parkinsonism (PD besides mutations in Park9, linked to a juvenile form of the disease. Here, we tested PK9-H with Cu(II and Ni(II ions, the former because it is an essential element ubiquitous in the human body, so its trafficking should be strictly regulated and one cannot exclude that Ypk9 may play a role in it, and the latter because, besides being a toxic element for many organisms and involved in different pathologies and inflammation states, it seems that the protein confers protection against it. NMR experiments showed that both cations can bind PK9-H in an effective way, leading to complexes whose coordination mode depends on the pH of the solution. NMR data have been used to build a model for the structure of the major Cu(II and Ni(II complexes. Structural changes in the conformation of the peptide with organized side chain orientation promoted by nickel coordination were detected.

  12. Inclusion complex of benzocaine and β-cyclodextrin: 1H NMR and isothermal titration calorimetry studies

    Science.gov (United States)

    Mic, Mihaela; Pırnǎu, Adrian; Bogdan, Mircea; Turcu, Ioan

    2013-11-01

    The supramolecular structure of the inclusion complex of β-cyclodextrin with benzocaine in aqueous solution has been investigated by 1H NMR spectroscopy and isothermal titration nanocalorimetry (ITC). Analysis of 1H NMR data by continuous variation method indicates that the benzocaine: β-cyclodextrin inclusion complex occurs and has a 1:1 stoichiometry. Rotating frame NOE spectroscopy (ROESY) was used to ascertain the solution geometry of the host-guest complex which indicates that the benzocaine molecule was included with the aromatic ring into the cyclodextrin cavity. Although the affinity of benzocaine for cyclodextrin is relatively high, the association constant cannot be measured using ITC due to the low solubility of benzocaine in water.

  13. NMR-based metabonomic study on the subacute toxicity of aristolochic acid in rats.

    Science.gov (United States)

    Zhang, Xiaoyu; Wu, Huifeng; Liao, Peiqiu; Li, Xiaojing; Ni, Jiazuan; Pei, Fengkui

    2006-07-01

    The subacute toxicity of aristolochic acid (AA) was investigated by (1)H NMR spectroscopic and pattern recognition (PR)-based metabonomic methods. Model toxins were used to enable comparisons of the urinary profiles from rats treated with known toxicants and AA at various time intervals. Urinary (1)H NMR spectra were data-processed and analyzed by pattern recognition method. The result of visual comparison of the spectra showed that AA caused a renal proximal tubular and papillary lesion and a slight hepatic impair. Pattern recognition analysis indicated that the renal proximal tubule lesion was the main damage induced by AA, and the renal toxicity induced by AA was a progressive course with the accumulation of dosage by monitoring the toxicological processes from onset, development and part-recovery. These results were also supported by the conventional clinical biochemical parameters.

  14. NMR Study of Layered Transition Metal Ditelluride (Ir,Pt)Te2

    Science.gov (United States)

    Magishi, K.; Saito, T.; Koyama, K.; Matsumoto, N.; Nagata, S.

    2012-12-01

    We report the results of 125Te and 195Pt NMR measurements on (Ir,Pt)Te2 in order to elucidate the characteristic electronic states. For PtTe2, the NMR spectrum exhibits a sharp line, which shows the uniaxially symmetric powder pattern due to the anisotropic Knight shift. The Knight shift is almost independent of temperature and is larger than that for IrTe2. Also, the nuclear spin-lattice relaxation rate 1/T1 of PtTe2 is proportional to the temperature in a wide temperature range, that is, obeys the Korringa relation as expected for simple metallic systems. From the analyses of the Knight shift and 1/T1, it is suggested that the antiferromagnetic correlations slightly exist.

  15. CD and 31P NMR studies of tachykinin and MSH neuropeptides in SDS and DPC micelles

    Science.gov (United States)

    Schneider, Sydney C.; Brown, Taylor C.; Gonzalez, Javier D.; Levonyak, Nicholas S.; Rush, Lydia A.; Cremeens, Matthew E.

    2016-02-01

    Secondary structural characteristics of substance P (SP), neurokinin A (NKA), neurokinin B (NKB), α-melanocyte stimulating hormone peptide (α-MSH), γ1-MSH, γ2-MSH, and melittin were evaluated with circular dichroism in phosphite buffer, DPC micelles, and SDS micelles. CD spectral properties of γ1-MSH and γ2-MSH as well as 31P NMR of DPC micelles with all the peptides are reported for the first time. Although, a trend in the neuropeptide/micelle CD data appears to show increased α-helix content for the tachykinin peptides (SP, NKA, NKB) and increased β-sheet content for the MSH peptides (α-MSH, γ1-MSH, γ2-MSH) with increasing peptide charge, the lack of perturbed 31P NMR signals for all neuropeptides could suggest that the reported antimicrobial activity of SP and α-MSH might not be related to a membrane disruption mode of action.

  16. NMR Study on the Inclusion Complexes of β-Cyclodextrin with Isoflavones.

    Science.gov (United States)

    Zhao, Rui; Sandström, Corine; Zhang, Haiyang; Tan, Tianwei

    2016-03-28

    The structure of the inclusion complexes of β-cyclodextrin (β-CD) with daidzein and daidzin in D2O were investigated using NMR spectroscopy. For the β-CD and daidzein system, two types of 1:1 complexes were formed with the daidzein deeply inserted into the CD cavity with different orientations. For the β-CD/daidzin system, a 1:1 complex was formed with the flavonoid part of daidzin entering the CD cavity from the wide rim. The inclusion complexes determined by NMR were constructed using molecular docking. Furthermore, the mixture of puerarin, daidzein and daidzin, which are the major isoflavonoid components present in Radix puerariae, was analyzed by diffusion-ordered spectroscopy (DOSY) alone and upon addition of β-CD in order to mimic chromatographic conditions and compare their binding affinities.

  17. High-resolution /sup 1/H NMR study of the solution structure of delta-hemolysin

    Energy Technology Data Exchange (ETDEWEB)

    Tappin, M.J.; Pastore, A.; Norton, R.S.; Freer, J.H.; Campbell, I.D.

    1988-03-08

    The 26-residue toxin from Staphylococcus aureus delta-hemolysin, is thought to act by traversing the plasma membrane. The structure of this peptide, in methanol solution, has been investigated by using high-resolution NMR in combination with molecular dynamics calculations. The /sup 1/H NMR spectrum has been completely assigned, and it is shown that residues 2-20 form a relatively stable helix while the residues at the C-terminal end appear to be more flexible. The structures were calculated only from nuclear Overhauser effect data and standard bond lengths. It is shown that the results are consistent with /sup 3/J/sub NH-..cap alpha..CH/ coupling constants and amide hydrogen exchange rates.

  18. THE SYNTHESIS AND NMR STUDY ON THE STABILITY OF DIMETHYLMETHOXOPLATINUM(IV COMPLEXES

    Directory of Open Access Journals (Sweden)

    Sutopo Hadi

    2010-06-01

    Full Text Available he synthesis of two stable platinum(IV complexes containing methoxo ligand, [Pt(CH32(OCH3(OHpy2] (1 and fac-[Pt(CH32(OCH3(H2O3] (2, has been successfully performed. Complex 1 was prepared by oxidative addition reaction of cis-[Pt(CH32py2] with dry methanol, and a subsequent reaction of 1 with 70 % HClO4 in water produced the platinum complex 2. The stability of complex 2 in acidic aqueous solution was investigated and monitored with 1H and 195Pt NMR. The platinum complex 2 was found to be quite stable toward hydrolysis and no -hydride elimination was observed. Keywords: Methoxoplatinum(IV, NMR, complex stability, hydrolysis

  19. 11B-NMR study in boron-doped diamond films

    Directory of Open Access Journals (Sweden)

    H. Mukuda, T. Tsuchida, A. Harada, Y. Kitaoka, T. Takenouchi, Y. Takano, M. Nagao, I. Sakaguchi and H. Kawarada

    2006-01-01

    Full Text Available We have investigated an origin of the superconductivity discovered in boron (B-doped diamonds by means of 11B-NMR on heteroepitaxially grown (1 1 1 and (1 0 0 films and polycrystalline film. The characteristic difference of B-NMR spectral shape for the (1 1 1 and (1 0 0 thin films is demonstrated as arising from the difference in the concentration (nB(1 of boron substituted for carbon. It is revealed from a scaling between a superconducting transition temperature Tc and nB(1 that the holes doped into diamond via the substitution of boron for carbon are responsible for the onset of superconductivity. The result suggests that the superconductivity in boron-doped diamond is mediated by the electron–phonon interaction brought about a high Debye temperature ~1860 K characteristic for the diamond structure.

  20. A Study of Quantum Error Correction by Geometric Algebra and Liquid-State NMR Spectroscopy

    CERN Document Server

    Sharf, Y; Somaroo, S S; Havel, T F; Knill, E H; Laflamme, R; Sharf, Yehuda; Cory, David G.; Somaroo, Shyamal S.; Havel, Timothy F.; Knill, Emanuel; Laflamme, Raymond

    2000-01-01

    Quantum error correcting codes enable the information contained in a quantum state to be protected from decoherence due to external perturbations. Applied to NMR, quantum coding does not alter normal relaxation, but rather converts the state of a ``data'' spin into multiple quantum coherences involving additional ancilla spins. These multiple quantum coherences relax at differing rates, thus permitting the original state of the data to be approximately reconstructed by mixing them together in an appropriate fashion. This paper describes the operation of a simple, three-bit quantum code in the product operator formalism, and uses geometric algebra methods to obtain the error-corrected decay curve in the presence of arbitrary correlations in the external random fields. These predictions are confirmed in both the totally correlated and uncorrelated cases by liquid-state NMR experiments on 13C-labeled alanine, using gradient-diffusion methods to implement these idealized decoherence models. Quantum error correcti...

  1. NMR Study on the Inclusion Complexes of β-Cyclodextrin with Isoflavones

    Directory of Open Access Journals (Sweden)

    Rui Zhao

    2016-03-01

    Full Text Available The structure of the inclusion complexes of β-cyclodextrin (β-CD with daidzein and daidzin in D2O were investigated using NMR spectroscopy. For the β-CD and daidzein system, two types of 1:1 complexes were formed with the daidzein deeply inserted into the CD cavity with different orientations. For the β-CD/daidzin system, a 1:1 complex was formed with the flavonoid part of daidzin entering the CD cavity from the wide rim. The inclusion complexes determined by NMR were constructed using molecular docking. Furthermore, the mixture of puerarin, daidzein and daidzin, which are the major isoflavonoid components present in Radix puerariae, was analyzed by diffusion-ordered spectroscopy (DOSY alone and upon addition of β-CD in order to mimic chromatographic conditions and compare their binding affinities.

  2. Rotational energy barrier of 2-(2',6'-dihydroxyphenyl)benzoxazole: a case study by NMR.

    Science.gov (United States)

    Chen, Weihua; Twum, Eric B; Li, Linlin; Wright, Brian D; Rinaldi, Peter L; Pang, Yi

    2012-01-01

    2-(2'-Hydroxyphenyl)benzoxazole (HBO) derivatives represent an important class of luminescent materials, as they can undergo excited state intramolecular proton transfer (ESIPT). The material's ESIPT properties are dependent on the ratio of two different rotamers, whose interconversion is poorly understood. By using HBO derivative 4, the rotational energy barrier of 2- (2',6'-hydroxyphenyl)benzoxazole is determined to be 10.5 kcal/mol by variable-temperature NMR. Although a HBO derivative typically exhibits two rotamers with O···H-O (e.g., 1a) and N···H-O bonding (e.g., 1b), correlation of NMR with fluorescence data reveals that the rotamer with N···H-O bonding is predominant in the solution.

  3. NMR studies on the new iron arsenide superconductors including the superconducting state

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, Hans-Joachim; Lang, Guillaume; Hammerath, Franziska; Manthey, Katarina; Behr, Guenther; Werner, Jochen; Buechner, Bernd [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Paar, Dalibor [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Dept. of Physics, Faculty of Science, Univ. of Zagreb (Croatia); Curro, Nicholas [Dept. of Physics, Univ. of California, Davis, CA 95616 (United States)

    2009-07-01

    We summarize our Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) results on the new iron arsenide superconductor LaO{sub 1-x}F{sub x}FeAs in the normal state, and show new NMR data in the superconducting state. Beyond early evidence of nodes and spin-singlet pairing[2], we find evidence of a deviation of the T{sup 3} behaviour of the spin lattice relaxation rate, 1/T{sub 1}, at temperatures significantly below T{sub c}, which would agree with the suggested extended s-wave symmetry. The deviation of the T{sup 3} behaviour is induced by the pair breaking effect of impurities. Different amounts of impurities would lead to different temperature dependences of 1/T{sub 1}, which would allow to differentiate between d-wave and extended s-wave symmetries.

  4. A 19F NMR study of C-I....pi- halogen bonding

    DEFF Research Database (Denmark)

    Hauchecorne, Dieter; vand er Veken, Benjamin J.; Herrebout, Wouter A.;

    2011-01-01

    The formation of halogen bonded complexes between toluene-d8 and the perfluoroiodopropanes 1-C3F7I and 2-C3F7I has been investigated using 19F NMR spectroscopy. For both Lewis acids, evidence was found for the formation of a C–I⋯π halogen bonded complex. The complex formed is a 1:1 type. Using sp...

  5. A NMR STUDY OF DRYOCRASSINE%绵马贯众素的NMR研究

    Institute of Scientific and Technical Information of China (English)

    肖国君; 叶利民; 苏甫; 周游

    2004-01-01

    从绵马贯众(Dryopteris crassirhizoma)中分离得到绵马贯众素, 应用1D NMR和2D NMR(1 H-1 H COSY, HMQC, HMBC)技术, 尤其是HMBC谱确证了绵马贯众素的结构, 并对其 13C化学位移进行了明确的归属.

  6. NMR Studies of Mass Transport in New Conducting Media for Fuel Cells

    Science.gov (United States)

    2009-01-01

    D’Epifanio, Debora Marani, Michele Vittadello, and Jayakody R. P. Jayakody, Journal of the Electrochemical Society , 153 A1226-A1231 (2006). 7...Durantino, H. Zhang, L. Xiao, and B. Benicewicz, Journal of the Electrochemical Society , 154, B242 (2007). 12. "NMR Characterization of Composite Polymer...Membranes for Low Humidity PEM Fuel Cells", with Isabella Nicotera, Tao Zhang, and Andrew Bocarsly, Journal of the Electrochemical Society , L54, B466

  7. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  8. NMR studies on 1,3-dipolar cycloaddition of nitrile oxides to norbornenes

    Energy Technology Data Exchange (ETDEWEB)

    Gucma, Miroslaw; Golebiewski, W. Marek; Krawczyk, Maria, E-mail: golebiewski@ipo.waw.pl [Institute of Industrial Organic Chemistry, Warsaw (Poland)

    2013-05-15

    The 1,3-dipolar cycloaddition reaction of nitrile oxides to norbornenes substituted with an acrylate-derived moiety was examined. Only adducts to norbornene system were formed with a good exo selectivity and complete site-selectivity. Structures of the products were elucidated by an extensive application of electrospray ionization-mass spectrometry (ESI-MS) and 2D {sup 1}H and {sup 13}C nuclear magnetic resonance (NMR). (author)

  9. A Comparative Study of Different Amorphous and Paracrystalline Silica by NMR and SEM/EDS

    Institute of Scientific and Technical Information of China (English)

    JIA Yuan; WANG Baomin; ZHANG Tingting

    2015-01-01

    This work aimed to research the structure models of amorphous materials. Five amorphous and paracrystalline samples (natural or artiifcial) were investigated via29Si/27Al nuclear magnetic resonance (NMR) and field emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS). The results of NMR showed the resonances of different specimens:-93.2 ppm,-101.8 ppm,-111.8 ppm for natural pozzolana opal shale (POS). These peaks were assigned to the Q2(2OH), Q3(OH)/Q4(1Al) and Q4 respectively. The results of27Al MAS NMR indicated that Al substituted for Si site in tetrahedral existing in the POS, while the Al/Si atomic ratio in opal was low (around 0.04). For the alkali-silicate-hydrate gel, there were at least three resolved signals assigned to Q0 and Q1, respectively. For the fused silica glass powder, there were the primary signals centered about at the range from-107 to-137 ppm, which were assigned to Q4 units. In addition, the peaks at around-98 and-108 ppm were corresponding to Q3(1OH) and Q4 units existing in aerogel silica structure.

  10. La-NMR study on a La dilute system of PrPb{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Y; Sakai, H; Chudo, H; Kambe, S; Yasuoka, H [ASRC, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Suzuki, H S [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Homma, Y; Aoki, D; Shiokawa, Y, E-mail: tokunaga.yo@jaea.go.j [IMR Tohoku University, Narita Oarai Higashiibaraki Ibaraki 311-1313 (Japan)

    2009-03-01

    We report the first {sup 139} La-NMR measurements on a La dilute system of PrPb{sub 3}. We have succeeded to detect {sup 139}La-NMR signal on a powder sample of Pr{sub 0.97}La{sub 0.03}Pb{sub 3} and extracted the temperature dependence of the Knight shift{sup 139}La K(T) in a temperature range between 1.5 and 220 K. K(T) has been found to maintain a linear relation with the bulk-susceptibility {sub chi}(T){sup bulk} in wide temperature range, except for a small deviation in the temperature region below 6 K. The slopes of the{sup 139} K vs nu{sup bulk} plots yield for the hyperfine coupling constants A{sub hf} the value 375 Oe/muB. From the NMR results, we discuss the effect of the La substitutions on microscopic magnetic properties of PrPb{sub 3}.

  11. NMR study on a novel mucin from jellyfish in natural abundance, Qniumucin from Aurelia aurita.

    Science.gov (United States)

    Uzawa, Jun; Urai, Makoto; Baba, Takayuki; Seki, Hiroko; Taniguchi, Kayoko; Ushida, Kiminori

    2009-05-22

    A novel mucin (qniumucin), which we recently discovered in jellyfish, was investigated by several NMR techniques. Almost all the peaks in the (13)C and proton NMR spectra were satisfactorily assigned to the amino acids in the main chain and to the bridging GalNAc, the major sugar in the saccharide branches. The amino acid sequence in the tandem repeat part (-VVETTAAP-) was reconfirmed by the cross-peaks between alpha protons and carbonyl carbons in the HMBC spectrum. A connectivity analysis around the O-glycoside bond (GalNAc-Thr) was also performed, and detailed information on the local configuration was obtained by the DPFGSE-NOE-HSD technique. The strategy and the results described in this paper can be extended to the structural analysis of general O-glycan chains, which are more complex than the present mucin. NMR analyses reveal the simple structure of qniumucin extracted by the present protocol, and the homogeneity and purity of qniumucin are probably the result of it being extracted from jellyfish, a primitive animal.

  12. Molecular structure of crude beeswax studied by solid-state 13C NMR.

    Science.gov (United States)

    Kameda, Tsunenori

    2004-01-01

    13C solid-state NMR experiments were performed to investigate the structure of beeswax in the native state (crude beeswax) for the first time. From quantitative direct polarization 13C MAS NMR spectrum, it was found that the fraction of internal-chain methylene (int-(CH2)) component compared to other components of crude beeswax was over 95%. The line shape of the int-(CH2) carbon resonance region was comprehensively analyzed in terms of NMR chemical shift. The 13C broad peak component covering from 31 to 35 ppm corresponds to int-(CH2) carbons with trans conformation in crystalline domains, whereas the sharp signal at 30.3 ppm corresponds to gauche conformation in the non-crystalline domain. From peak deconvolution of the aliphatic region, it was found that over 85% of the int-(CH2) has a crystal structure and several kinds of molecular packing for int-(CH2), at least three, exist in the crystalline domain.

  13. Infrared and MAS NMR Spectroscopic Studies of Al18B4O33

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The IR spectrum and 11B and 27Al MAS NMR spectra of Al18B4O33 are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms. TheIR spectrum shows that the strong vibrations of the BO3 groups are present in the 1 500~1 200em-1 region, and very weak bands of BO4 units are present in the region from 1 000 to 1 100cm-1. 11B MAS NMR spectrum indicates that the strong signal for BO3 units appears in the region from δ +5 to δ +20, and the very weak signal for BO4 units is at about δ-1, while 27AlMAS NMR spectrum shows five peaks at about δ +62, +42. 1, +14,-4.7 and-6.4, originating from AlO4, AlO4, A1O5, AlO6 and AlO6, respectively. These results reveal that there areminor BO4 units in Al18B4O33, indicating that a small amount of B atoms substitute for Al atomsin the 4-fold coordination.

  14. Tracing the origin of beer samples by NMR and chemometrics: Trappist beers as a case study.

    Science.gov (United States)

    Mannina, Luisa; Marini, Federico; Antiochia, Riccarda; Cesa, Stefania; Magrì, Antonio; Capitani, Donatella; Sobolev, Anatoly P

    2016-10-01

    An NMR and chemometric analytical approach to classify beers according to their brand identity was developed within the European TRACE project (FP6-2003-FOOD-2-A, contract number: 0060942). Rochefort 8 Trappist beers (47 samples), other Trappist beers (76 samples) and non-Trappist beers (110 samples) were analyzed by (1) H NMR spectroscopy. Selected NMR signals were measured and used to build classification models. Three different classification problems were identified, namely Trappist versus non-Trappist, Rochefort versus Non-Rochefort, and Rochefort 8 versus non-Rochefort 8. In all the three cases, both a discriminant and a modeling approaches were followed, using partial least squares discriminant analysis (PLS-DA) and soft independent modeling of class analogies (SIMCA), respectively, leading to very high classification accuracy as evaluated by external validation. Information regarding chemical composition was also obtained: Trappist beers contain a higher amount of formic and pyruvic acids and a lower amount of acetic acid and alanine with respect to non-Trappist ones. Rochefort beers turned out to have also a higher content of propanol and isopentanol with respect to non-Rochefort samples. Finally, Rochefort 8, shows the highest content of pyruvic acid and the lowest content of gallic, fumaric, acetic acids, adenosine, uridine, 2-phenylethanol, GABA, and alanine.

  15. Solid-state NMR paramagnetic relaxation enhancement immersion depth studies in phospholipid bilayers

    KAUST Repository

    Chu, Shidong

    2010-11-01

    A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine (PSPC) phospholipid bilayers as paramagnetic moieties and the resulting enhancements of the longitudinal relaxation (T1) times of 31P nuclei on the surface of the bilayers were measured by a standard inversion recovery pulse sequence. The 31P NMR spin-lattice relaxation times decrease steadily as the DOXYL spin label moves closer to the surface as well as the concentration of the spin-labeled lipids increase. The enhanced relaxation vs. the position and concentration of spin-labels indicate that PRE induced by the DOXYL spin label are significant to determine longer distances over the whole range of the membrane depths. When these data were combined with estimated correlation times τc, the r-6-weighted, time-averaged distances between the spin-labels and the 31P nuclei on the membrane surface were estimated. The application of using this solid-state NMR PRE approach coupled with site-directed spin labeling (SDSL) may be a powerful method for measuring membrane protein immersion depth. © 2010 Elsevier Inc. All rights reserved.

  16. Study of conformation and dynamic of surfactant molecules in graphite oxide via NMR

    Energy Technology Data Exchange (ETDEWEB)

    Ai, X.Q. [Jiangsu Second Normal University, College of Physics and Electronic Engineering, Nanjing (China); Ma, L.G. [Nanjing Xiaozhuang University, School of Electronic Engineering, Nanjing (China)

    2016-08-15

    The conformation and dynamic of surfactant in graphite oxide (GO) was investigated by solid-state {sup 13}C magic-angle-spinning NMR and {sup 1}H-{sup 13}C cross-polarization/magic-angle-spinning NMR spectra. The conformation ordering of the alkyl chains in the confined system shows strong dependence on its orientation. While the alkyl chains parallel to the GO layer in lateral monolayer arrangement are in gauche conformation in addition to a small amount of all-trans conformation, those with orientation radiating away from the GO in paraffin bilayer arrangement is in all-trans conformation in addition to some gauche conformation even though high-order diffraction peaks appears. NMR results suggest that the least mobile segment is located at the GO-surfactant interface corresponding to the N-methylene group. Further from it, the mobility of the alkyl chain increases. The terminal methyl and N-methyl carbon groups have the highest mobile. The chains in all-trans conformational state are characterized as more rigid than chains with gauche conformation; each segment of the confined alkyl chains with the lateral monolayer arrangement exhibits less mobility as compared to that with the paraffin bilayer arrangement. (orig.)

  17. Segmental isotope labeling of proteins for NMR structural study using a protein S tag for higher expression and solubility

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hiroshi [Center for Advanced Biotechnology and Medicine, Department of Biochemistry, Robert Wood Johnson Medical School (United States); Swapna, G. V. T. [State University of New Jersey, Department of Molecular Biology and Biochemistry, and Northeast Structural Genomics Consortium, Rutgers (United States); Wu, Kuen-Phon; Afinogenova, Yuliya [Center for Advanced Biotechnology and Medicine, Department of Biochemistry, Robert Wood Johnson Medical School (United States); Conover, Kenith; Mao, Binchen [State University of New Jersey, Department of Molecular Biology and Biochemistry, and Northeast Structural Genomics Consortium, Rutgers (United States); Montelione, Gaetano T.; Inouye, Masayori, E-mail: inouye@cabm.rutgers.edu [Center for Advanced Biotechnology and Medicine, Department of Biochemistry, Robert Wood Johnson Medical School (United States)

    2012-04-15

    A common obstacle to NMR studies of proteins is sample preparation. In many cases, proteins targeted for NMR studies are poorly expressed and/or expressed in insoluble forms. Here, we describe a novel approach to overcome these problems. In the protein S tag-intein (PSTI) technology, two tandem 92-residue N-terminal domains of protein S (PrS{sub 2}) from Myxococcus xanthus is fused at the N-terminal end of a protein to enhance its expression and solubility. Using intein technology, the isotope-labeled PrS{sub 2}-tag is replaced with non-isotope labeled PrS{sub 2}-tag, silencing the NMR signals from PrS{sub 2}-tag in isotope-filtered {sup 1}H-detected NMR experiments. This method was applied to the E. coli ribosome binding factor A (RbfA), which aggregates and precipitates in the absence of a solubilization tag unless the C-terminal 25-residue segment is deleted (RbfA{Delta}25). Using the PrS{sub 2}-tag, full-length well-behaved RbfA samples could be successfully prepared for NMR studies. PrS{sub 2} (non-labeled)-tagged RbfA (isotope-labeled) was produced with the use of the intein approach. The well-resolved TROSY-HSQC spectrum of full-length PrS{sub 2}-tagged RbfA superimposes with the TROSY-HSQC spectrum of RbfA{Delta}25, indicating that PrS{sub 2}-tag does not affect the structure of the protein to which it is fused. Using a smaller PrS-tag, consisting of a single N-terminal domain of protein S, triple resonance experiments were performed, and most of the backbone {sup 1}H, {sup 15}N and {sup 13}C resonance assignments for full-length E. coli RbfA were determined. Analysis of these chemical shift data with the Chemical Shift Index and heteronuclear {sup 1}H-{sup 15}N NOE measurements reveal the dynamic nature of the C-terminal segment of the full-length RbfA protein, which could not be inferred using the truncated RbfA{Delta}25 construct. CS-Rosetta calculations also demonstrate that the core structure of full-length RbfA is similar to that of the RbfA{Delta}25

  18. Epitope Mapping of Antigenic MUC1 Peptides to Breast Cancer Antibody Fragment B27.29: A Heteronuclear NMR Study

    Energy Technology Data Exchange (ETDEWEB)

    Grinstead, Jeffrey S.; Schuman, Jason T.; Campbell, Ann P.

    2003-11-13

    MUC1 mucin is a breast cancer-associated transmembrane glycoprotein, of which the extracellular domain is formed by the repeating 20-amino acid sequence GVTSAPDTRPAPGSTAPPAH. In neoplastic breast tissue, the highly immunogenic sequence PDTRPAP (in bold above) is exposed. Antibodies raised directly against MUC1-expressing tumors offer unique access to this neoplastic state, as they represent immunologically relevant ''reverse templates'' of the tumor-associated mucin. In a previous study [Grinstead, J. S., et al. (2002) Biochemistry 41, 9946-9961], 1H NMR methods were used to correlate the effects of cryptic glycosylation outside of the PDTRPAP core epitope sequence on the recognition and binding of Mab B27.29, a monoclonal antibody raised against breast tumor cells. In the study presented here, isotope-edited NMR methods, including 15N and 13C relaxation measurements, were used to probe the recognition and binding of the PDTRPAP epitope sequence to Fab B27.29. Two peptides were studied: a one-repeat MUC1 16mer peptide of the sequence GVTSAPDTRPAPGSTA and a two-repeat MUC1 40mer peptide of the sequence (VTSAPDTRPAPGSTAPPAHG)2. 15N and 13C NMR relaxation parameters were measured for both peptides free in solution and bound to Fab B27.29. The 13CR T1 values best represent changes in the local correlation time of the peptide epitope upon binding antibody, and demonstrate that the PDTRPAP sequence is immobilized in the antibody-combining site. This result is also reflected in the appearance of the 15N- and 13C-edited HSQC spectra, where line broadening of the same peptide epitope resonances is observed. The PDTRPAP peptide epitope expands upon the peptide epitope identified previously in our group as PDTRP by homonuclear NMR experiments [Grinstead, J. S., et al. (2002) Biochemistry 41, 9946-9961], and illustrates the usefulness of the heteronuclear NMR experiments. The implications of these results are discussed within the context of MUC1 breast

  19. Radiation damping in microcoil NMR probes.

    Science.gov (United States)

    Krishnan, V V

    2006-04-01

    Radiation damping arises from the field induced in the receiver coil by large bulk magnetization and tends to selectively drive this magnetization back to equilibrium much faster than relaxation processes. The demand for increased sensitivity in mass-limited samples has led to the development of microcoil NMR probes that are capable of obtaining high quality NMR spectra with small sample volumes (nL-microL). Microcoil probes are optimized to increase sensitivity by increasing either the sample-to-coil ratio (filling factor) of the probe or quality factor of the detection coil. Though radiation damping effects have been studied in standard NMR probes, these effects have not been measured in the microcoil probes. Here a systematic evaluation of radiation damping effects in a microcoil NMR probe is presented and the results are compared with similar measurements in conventional large volume samples. These results show that radiation-damping effects in microcoil probe is much more pronounced than in 5 mm probes, and that it is critically important to optimize NMR experiments to minimize these effects. As microcoil probes provide better control of the bulk magnetization, with good RF and B0 inhomogeneity, in addition to negligible dipolar field effects due to nearly spherical sample volumes, these probes can be used exclusively to study the complex behavior of radiation damping.

  20. Mechanism of Solid-State Thermolysis of Ammonia Boraine: 15N NMR Study Using Fast Magic-Angle Spinning and Dynamic Nuclear Polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Takeshi [Ames Laboratory; Gupta, Shalabh [Ames Laboratory; Caporini, Marc A [Bruker BioSpin Corporation; Pecharsky, Vitalij K [Ames Laboratory; Pruski, Marek [Ames Laboratory

    2014-08-28

    The solid-state thermolysis of ammonia borane (NH3BH3, AB) was explored using state-of-the-art 15N solid-state NMR spectroscopy, including 2D indirectly detected 1H{15N} heteronuclear correlation and dynamic nuclear polarization (DNP)-enhanced 15N{1H} cross-polarization experiments as well as 11B NMR. The complementary use of 15N and 11B NMR experiments, supported by density functional theory calculations of the chemical shift tensors, provided insights into the dehydrogenation mechanism of AB—insights that have not been available by 11B NMR alone. Specifically, highly branched polyaminoborane derivatives were shown to form from AB via oligomerization in the “head-to-tail” manner, which then transform directly into hexagonal boron nitride analog through the dehydrocyclization reaction, bypassing the formation of polyiminoborane.

  1. Studies of Ga NMR and NQR in SrGa4

    Science.gov (United States)

    Niki, H.; Higa, N.; Nakamura, S.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y.; Harima, H.

    2015-04-01

    In order to microscopically investigate the properties in SrGa4, the Ga NMR measurements of a powder sample were carried out. The Ga NMR spectra corresponding to Ga(I) and Ga(II) sites are obtained. The NMR spectra of 69&71Ga (a nuclear spin I = 3/2) in the powder sample of SrGa4 do not take a typical powder pattern caused by the NQR interaction, but take the spectra consisting of three well resolved resonance-lines, which indicates that the nonuniform distribution of crystal orientation in the powder sample occurs because of the magnetic anisotropy. From the analysis of the Ga NMR spectrum, it is found that the ab-plane of the crystal is parallel to the external magnetic field, which would be attributed to the anisotropy of the magnetic susceptibility with the easy axis parallel to the ab-plane. This result is also confirmed by the 69Ga NQR in SrGa4. The Knight shifts of the 69Ga(I) and 69Ga(II) shift slightly to the negative side with decreasing temperature due to the core polarization of the d-electrons. The values of the Knight shift of the 69Ga(I) and 69Ga(II) are 0.01 and -0.11 % at 4.2 K, and 0.09 and -0.08 % at 300 K, respectively. The values of the 1/ T 1 T of the NMR of both 69Ga(I) and 69Ga(II) are almost constant between 4.2 and 100 K, whose values are 1.5 s -1 K -1 at 69Ga(I) and 0.12 s -1 K -1 at 69Ga(II), while the 1/ T 1 T slightly increase above 100K with increasing temperature. The value of T 1 of 69Ga(I) is one order of magnitude less than that of 69Ga(II).

  2. Studies of Ga NMR and NQR in SrGa{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Niki, H., E-mail: niki@sci.u-ryukyu.ac.jp; Higa, N.; Nakamura, S.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y. [University of the Ryukyus, Faculty of Science (Japan); Harima, H. [Kobe University, Faculty of Science (Japan)

    2015-04-15

    In order to microscopically investigate the properties in SrGa{sub 4}, the Ga NMR measurements of a powder sample were carried out. The Ga NMR spectra corresponding to Ga(I) and Ga(II) sites are obtained. The NMR spectra of {sup 69&71}Ga (a nuclear spin I = 3/2) in the powder sample of SrGa{sub 4} do not take a typical powder pattern caused by the NQR interaction, but take the spectra consisting of three well resolved resonance-lines, which indicates that the nonuniform distribution of crystal orientation in the powder sample occurs because of the magnetic anisotropy. From the analysis of the Ga NMR spectrum, it is found that the ab-plane of the crystal is parallel to the external magnetic field, which would be attributed to the anisotropy of the magnetic susceptibility with the easy axis parallel to the ab-plane. This result is also confirmed by the {sup 69}Ga NQR in SrGa{sub 4}. The Knight shifts of the {sup 69}Ga(I) and {sup 69}Ga(II) shift slightly to the negative side with decreasing temperature due to the core polarization of the d-electrons. The values of the Knight shift of the {sup 69}Ga(I) and {sup 69}Ga(II) are 0.01 and –0.11 % at 4.2 K, and 0.09 and –0.08 % at 300 K, respectively. The values of the 1/ T{sub 1}T of the NMR of both {sup 69}Ga(I) and {sup 69}Ga(II) are almost constant between 4.2 and 100 K, whose values are 1.5 s {sup −1}K{sup −1} at {sup 69}Ga(I) and 0.12 s {sup −1}K{sup −1} at {sup 69}Ga(II), while the 1/ T{sub 1}T slightly increase above 100K with increasing temperature. The value of T{sub 1} of {sup 69}Ga(I) is one order of magnitude less than that of {sup 69}Ga(II)

  3. Molecular modeling and experimental studies on structure and NMR parameters of 9-benzyl-3,6-diiodo-9H-carbazole

    DEFF Research Database (Denmark)

    Radula-Janik, Klaudia; Kupka, Teobald; Ejsmont, Krzysztof;

    2015-01-01

    A combined experimental and theoretical study has been performed on 9-benzyl-3,6-diiodo-9H-carbazole. Experimental X-ray (100.0 K) and room-temperature 13C NMR studies were supported by advanced density functional theory (DFT) calculations. The non relativistic structure optimization was performed.......57 ppm dropped to 5.6 ppm). A good linear correlation between experimental and theoretically predicted structural and NMR parameters was observed....

  4. Surface Interactions and Confinement of Methane: A High Pressure Magic Angle Spinning NMR and Computational Chemistry Study

    Energy Technology Data Exchange (ETDEWEB)

    Ok, Salim; Hoyt, David W.; Andersen, Amity; Sheets, Julie; Welch, Susan A.; Cole, David R.; Mueller, Karl T.; Washton, Nancy M.

    2017-01-18

    Characterization and modeling of the molecular-level behavior of simple hydrocarbon gases, such as methane, in the presence of both nonporous and nano-porous mineral matrices allows for predictive understanding of important processes in engineered and natural systems. In this study, changes in local electromagnetic environments of the carbon atoms in methane under conditions of high pressure (up to 130 bar) and moderate temperature (up to 346 K) were observed with 13C magic-angle spinning (MAS) NMR spectroscopy while the methane gas was mixed with two model solid substrates: a fumed non-porous, 12 nm particle size silica and a mesoporous silica with 200 nm particle size and 4 nm average pore diameter. Examination of the interactions between methane and the silica systems over temperatures and pressures that include the supercritical regime was allowed by a novel high pressure MAS sample containment system, which provided high resolution spectra collected under in situ conditions. For pure methane, no significant thermal effects were found for the observed 13C chemical shifts at all pressures studied here (28.2 bar, 32.6 bar, 56.4 bar, 65.1 bar, 112.7 bar, and 130.3 bar). However, the 13C chemical shifts of resonances arising from confined methane changed slightly with changes in temperature in mixtures with mesoporous silica. The chemical shift values of 13C nuclides in methane change measurably as a function of pressure both in the pure state and in mixtures with both silica matrices, with a more pronounced shift when meso-porous silica is present. Molecular-level simulations utilizing GCMC, MD and DFT confirm qualitatively that the experimentally measured changes are attributed to interactions of methane with the hydroxylated silica surfaces as well as densification of methane within nanopores and on pore surfaces.

  5. Modelling catchment areas for secondary care providers: a case study.

    Science.gov (United States)

    Jones, Simon; Wardlaw, Jessica; Crouch, Susan; Carolan, Michelle

    2011-09-01

    Hospitals need to understand patient flows in an increasingly competitive health economy. New initiatives like Patient Choice and the Darzi Review further increase this demand. Essential to understanding patient flows are demographic and geographic profiles of health care service providers, known as 'catchment areas' and 'catchment populations'. This information helps Primary Care Trusts (PCTs) to review how their populations are accessing services, measure inequalities and commission services; likewise it assists Secondary Care Providers (SCPs) to measure and assess potential gains in market share, redesign services, evaluate admission thresholds and plan financial budgets. Unlike PCTs, SCPs do not operate within fixed geographic boundaries. Traditionally, SCPs have used administrative boundaries or arbitrary drive times to model catchment areas. Neither approach satisfactorily represents current patient flows. Furthermore, these techniques are time-consuming and can be challenging for healthcare managers to exploit. This paper presents three different approaches to define catchment areas, each more detailed than the previous method. The first approach 'First Past the Post' defines catchment areas by allocating a dominant SCP to each Census Output Area (OA). The SCP with the highest proportion of activity within each OA is considered the dominant SCP. The second approach 'Proportional Flow' allocates activity proportionally to each OA. This approach allows for cross-boundary flows to be captured in a catchment area. The third and final approach uses a gravity model to define a catchment area, which incorporates drive or travel time into the analysis. Comparing approaches helps healthcare providers to understand whether using more traditional and simplistic approaches to define catchment areas and populations achieves the same or similar results as complex mathematical modelling. This paper has demonstrated, using a case study of Manchester, that when estimating

  6. Multinuclear NMR Study of the Solid Electrolyte Interface Formed in Lithium Metal Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chuan; Xu, Suochang; Hu, Mary Y.; Cao, Ruiguo; Qian, Jiangfeng; Qin, Zhaohai; Liu, Jun; Mueller, Karl T.; Zhang, Ji-Guang; Hu, Jian Zhi

    2017-04-18

    The composition of the solid electrolyte interphase (SEI) layers associated with a high performance Cu|Li cell using lithium bis(fluorosulfonyi)imide (LiFSI) in 1,2-dimethoxyethane (DME) as electrolyte is determined by a multinuclear (6Li, 19F, 13C and 1H) solid-state MAS NMR study at high magnetic field (850 MHz). This cell can be cycled at high rates (4 mA•cm-2) for more than 1000 cycles with no increase in the cell impedance at high Columbic efficiency (average of 98.4%) in a highly concentrated LiFSI-DME electrolyte (4 M). LiFSI, LiF, Li2O2 (and/or CH3OLi), LiOH, Li2S and Li2O are observed in the SEI and validated by comparing with the spectra acquired on standard compounds and literature reports. To gain further insight into the role of the solute and its concentration dependence on the formation of SEIs while keeping the solvent of DME unchanged, the SEIs from different concentrations of LiFSI-DME and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-DME electrolyte are also investigated. It is found that LiF, a lithiated compound with superior mechanical strength and good Li+ ionic conductivity, is observed in the concentrated 4.0 M LiFSI-DME and the 3.0 M LiTFSI-DME systems but not in the diluted 1.0 M LiFSI-DME system. Li2O exists in both low and high concentration of LiFSI-DME while no Li2O is observed in the LiTFSI system. Furthermore, the dead metallic Li is reduced in the 4 M LiFSI-DME system compared with that in the 1 M LiFSI-DME system. Quantitative 6Li MAS results indicate that the SEI associated with the 4 M LiFSI-DEME is denser or thicker than that of the 1 M LiFSI-DME and the 3 M LiTFSI-DME systems. These findings are likely the reasons for explaining the high electrochemical performance associated with the high concentration LiFSI-DME system.

  7. In vivo and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study; Espectroscopia `in vivo` e de alta resolucao em solidos por RMN: uma ferramenta para o estudo de plantas transgenicas

    Energy Technology Data Exchange (ETDEWEB)

    Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R. [EMBRAPA (Brazil). Centro Nacional de Pesquisa de Defesa da Agricultura; Bonagamba, T.J.; Panepucci, H. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica; Carneiro, M.; Rodrigues, C.A. [EMBRAPA (CENARGEN) (Brazil)

    1995-12-31

    This work has developed a study on transgenic plants using two different techniques of nuclear magnetic resonance, in vivo NMR and high resolution NMR. In order to understand the gene mutations and characterize the plants constituents, NMR spectral data were analysed and discussed, then the results were presented 2 refs., 4 figs.

  8. NMR ANALYSIS OF MALE FATHEAD MINNOW URINARY METABOLITES: A POTENTIAL APPROACH FOR STUDYING IMPACTS OF CHEMICAL EXPOSURES

    Science.gov (United States)

    The potential for profiling endogenous metabolites in urine from male fathead minnows (Pimephales promelas) to assess chemical exposures was explored using nuclear magnetic resonance (NMR) spectroscopy. Both one dimensional (1D) and two dimensional (2D) NMR spectroscopy w...

  9. A primer to nutritional metabolomics by NMR spectroscopy and chemometrics

    DEFF Research Database (Denmark)

    Savorani, Francesco; Rasmussen, Morten Arendt; Mikkelsen, Mette Skau

    2013-01-01

    This paper outlines the advantages and disadvantages of using high throughput NMR metabolomics for nutritional studies with emphasis on the workflow and data analytical methods for generation of new knowledge. The paper describes one-by-one the major research activities in the interdisciplinary...... structures for multivariate pattern recognition methods and (3) NMR for providing a unique fingerprint of the lipoprotein status of the subject. For the first time in history, by combining NMR spectroscopy and chemometrics we are able to perform inductive nutritional research as a complement to the deductive...

  10. New insight into the microtexture of chalks from NMR analysis

    DEFF Research Database (Denmark)

    Faÿ-Gomord, Ophélie; Soete, Jeroen; Katika, Konstantina

    2016-01-01

    quality chalks independently of their sedimentological and/or diagenetic history. The study aims to develop an NMR-based approach to characterize a broad range of chalk samples. The provided laboratory low-field NMR chalk classification can be used as a guide to interpret NMR logging data...... size and T2 logarithmic (T2lm) was calculated. It is apparent that tight chalks, whether their characteristics are sedimentological or diagenetic, yield smaller pore body sizes (T2lm well as narrower pore throats (average radius

  11. Interaction studies between periplasmic cytochromes provide insights into extracellular electron transfer pathways of Geobacter sulfurreducens.

    Science.gov (United States)

    Fernandes, Ana P; Nunes, Tiago C; Paquete, Catarina M; Salgueiro, Carlos A

    2017-02-20

    Geobacter bacteria usually prevail among other microorganisms in soils and sediments where Fe(III) reduction has a central role. This reduction is achieved by extracellular electron transfer (EET), where the electrons are exported from the interior of the cell to the surrounding environment. Periplasmic cytochromes play an important role in establishing an interface between inner and outer membrane electron transfer components. In addition, periplasmic cytochromes, in particular nanowire cytochromes that contain at least 12 haem groups, have been proposed to play a role in electron storage in conditions of an environmental lack of electron acceptors. Up to date, no redox partners have been identified in Geobacter sulfurreducens, and concomitantly, the EET and electron storage mechanisms remain unclear. In this work, NMR chemical shift perturbation measurements were used to probe for an interaction between the most abundant periplasmic cytochrome PpcA and the dodecahaem cytochrome GSU1996, one of the proposed nanowire cytochromes in G. sulfurreducens The perturbations on the haem methyl signals of GSU1996 and PpcA showed that the proteins form a transient redox complex in an interface that involves haem groups from two different domains located at the C-terminal of GSU1996. Overall, the present study provides for the first time a clear evidence for an interaction between periplasmic cytochromes that might be relevant for the EET and electron storage pathways in G. sulfurreducens. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  12. Lessons from VET Providers Delivering Degrees: Case Studies. Support Document

    Science.gov (United States)

    Callan, Victor J.; Bowman, Kaye

    2015-01-01

    The recent growth in the number of registered vocational education and training (VET) providers delivering associate degrees and bachelor degrees in their own right has been well publicized. However, little is known about why these VET providers have made this transition, what support is being provided to their staff and students, and how the…

  13. Structure and disorder in iron-bearing sodium silicate glasses and melts: High-resolution 29Si and 17O solid-state NMR study

    Science.gov (United States)

    Kim, H.; Lee, S.

    2012-12-01

    Understanding of the effect of iron content on the structure (Si coordination environment and the degree of polymerization) of iron-bearing silicate melts and glasses is essential for studying their macroscopic properties and diverse geological processes in Earth's interior. Although the recent advances in high-resolution solid-state NMR techniques provide detailed structural information of a diverse iron-free oxide glasses with varying composition (e.g., Lee, P. Natl. Acad. Sci. USA., 2011, 108, 6847; Lee and Sung, Chem. Geol., 2008, 256, 326; Park and Lee, Geochim. Cosmochim. Acta, 2012, 80, 125; Lee et al., Phys. Rev., 103, 095501, 2009), their application to iron-bearing silicate glasses has a limited usefulness in resolving atomic configurations due to the effect of paramagnetic cation (i.e., Fe) on the NMR spectra. Here, we report the first ^{29}Si and ^{17}O NMR spectra for sodium-iron silicate glasses with varying iron content (Na_{2}O-Fe_{2}O_{3}-SiO_{2} glasses, up to 34.60 wt% Fe_{2}O_{3}), revealing previously unknown details of iron-induced changes in structure and disorder. While signal intensity decreases and peak width increases exponentially with increasing iron content [=Fe_{2}O_{3}/(Na_{2}O+Fe_{2}O_{3})], ^{29}Si MAS NMR spectra for sodium-iron silicate glasses present the slight peak shift and an asymmetrical peak broadening toward higher Q^{n} species with increasing iron content. This result implies an increase in the degree of polymerization with increasing iron content. Additionally, ^{29}Si spin-relaxation time (T_{1}) for the glasses decreases with increasing of iron content by several orders of magnitude. ^{17}O 3QMAS NMR spectra for the glasses show well-resolved non-bridging oxygen (NBO, Na-O-Si) and bridging oxygen (BO, Si-O-Si) even at relatively high iron content, providing the first direct experimental estimation of the degree of polymerization. In sodium-iron silicate glasses, the fraction of NBO decreases with increasing iron

  14. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

  15. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

  16. A study on the NMR spectrum of monoterpene glucosides from Paeonia lactiflora Pall.%芍药单萜苷的NMR谱学研究

    Institute of Scientific and Technical Information of China (English)

    张晓燕; 王金辉; 李铣

    2001-01-01

    A study on the NMR spectral character of paeoniflorin, amonoterpene glucoside, was carried out and its proton signals of 1H-NMR were completely assigned by means of HMQC、HMBC、1H-1H COSY and ROSEY for the first time.%利用HMBC,HMQC,1H-1HCOSY,ROSEY等核磁技术第一次完整地确定了芍药苷中碳氢信号的归属。

  17. A 1H-NMR-Based Metabonomic Study on the Anti-Depressive Effect of the Total Alkaloid of Corydalis Rhizoma

    Directory of Open Access Journals (Sweden)

    Hongwei Wu

    2015-05-01

    Full Text Available Corydalis Rhizoma, named YuanHu in China, is the dried tuber of Corydalis yanhusuo W.T. Wang which is used in Traditional Chinese Medicine for pain relief and blood activation. Previous pharmacological studies showed that apart from analgesics, the alkaloids from YuanHu may be useful in the therapy of depression by acting on the GABA, dopamine and benzodiazepine receptors. In this study, the antidepressive effect of the total alkaloid of YuanHu (YHTA was investigated in a chronic unpredictable mild stress (CUMS rat model using 1H-NMR-based metabonomics. Plasma metabolic profiles were analyzed and multivariate data analysis was applied to discover the metabolic biomarkers in CUMS rats. Thirteen biomarkers of CUMS-introduced depression were identified, which are myo-inositol, glycerol, glycine, creatine, glutamine, glutamate, β-glucose, α-glucose, acetoacetate, 3-hydroxybutyrate, leucine and unsaturated lipids (L7, L9. Moreover, a metabolic network of the potential biomarkers in plasma perturbed by CUMS was detected. After YHTA treatment, clear separation between the model group and YHTA-treated group was achieved. The levels of all the abnormal metabolites mentioned above showed a tendency of restoration to normal levels. The results demonstrated the therapeutic efficacy of YHTA against depression and suggested that NMR-based metabolomics can provide a simple and easy tool for the evaluation of herbal therapeutics.

  18. Hydrocarbons depending on the chain length and head group adopt different conformations within a water-soluble nanocapsule: 1H NMR and molecular dynamics studies.

    Science.gov (United States)

    Choudhury, Rajib; Barman, Arghya; Prabhakar, Rajeev; Ramamurthy, V

    2013-01-10

    In this study we have examined the conformational preference of phenyl-substituted hydrocarbons (alkanes, alkenes, and alkynes) of different chain lengths included within a confined space provided by a molecular capsule made of two host cavitands known by the trivial name "octa acid" (OA). One- and two-dimensional (1)H NMR experiments and molecular dynamics (MD) simulations were employed to probe the location and conformation of hydrocarbons within the OA capsule. In general, small hydrocarbons adopted a linear conformation while longer ones preferred a folded conformation. In addition, the extent of folding and the location of the end groups (methyl and phenyl) were dependent on the group (H(2)C-CH(2), HC═CH, and C≡C) adjacent to the phenyl group. In addition, the rotational mobility of the hydrocarbons within the capsule varied; for example, while phenylated alkanes tumbled freely, phenylated alkenes and alkynes resisted such a motion at room temperature. Combined NMR and MD simulation studies have confirmed that molecules could adopt conformations within confined spaces different from that in solution, opening opportunities to modulate chemical behavior of guest molecules.

  19. Cycloalkane and alicyclic heterocycle complexation by new switchable resorcin[4]arene-based container molecules: NMR and ITC binding studies.

    Science.gov (United States)

    Hornung, Jens; Fankhauser, Daniel; Shirtcliff, Laura D; Praetorius, Antonia; Schweizer, W Bernd; Diederich, François

    2011-10-24

    The synthesis and structural characterization of novel, "molecular basket"-type bridged cavitands is reported. The resorcin[4]arene-based container molecules feature well-defined cavities that bind a wide variety of cycloalkanes and alicyclic heterocycles. Association constants (K(a)) of the 1:1 inclusion complexes were determined by both (1)H NMR and isothermal titration calorimetry (ITC). The obtained K(a) values in mesitylene ranged from 1.7×10(2) M(-1) for cycloheptane up to 1.7×10(7) M(-1) for morpholine. Host-guest complexation by the molecular baskets is generally driven by dispersion interactions, C-H···π interactions of the guests with the aromatic walls of the cavity, and optimal cavity filling. Correlations between NMR-based structural data and binding affinities support that the complexed heterocyclic guests undergo additional polar C-O···C=O, N-H···π, and S···π interactions. The first crystal structure of a cavitand-based molecular basket is reported, providing precise information on the geometry and volume of the inner cavity in the solid state. Molecular dynamic (MD) simulations provided information on the size and conformational preorganization of the cavity in the presence of encapsulated guests. The strongest binding of heterocyclic guests, engaging in polar interactions with the host, was observed at a cavity filling volume of 63 ± 9%.

  20. Barbiturate bearing aroylhydrazine derivatives: Synthesis, NMR investigations, single crystal X-ray studies and biological activity

    Science.gov (United States)

    Giziroglu, Emrah; Sarikurkcu, Cengiz; Aygün, Muhittin; Basbulbul, Gamze; Soyleyici, H. Can; Firinci, Erkan; Kirkan, Bulent; Alkis, Ayse; Saylica, Tayfur; Biyik, Halil

    2016-03-01

    A series of barbituric acid aroylhydrazine derivatives have been prepared from their corresponding 1,3-dimethyl-5-acetyl barbituric acid and aroylhydrazines. All compounds have been fully characterized by using FT-IR, multinuclear NMR (1H, 13C) and Mass (MS) spectrometry. We also describe the X-ray crystal structure of 3a, which crystallizes in the monoclinic P21/n space group. The crystal structure is stabilized with infinite linear chains of dimeric units. Furthermore, all compounds were investigated for their tyrosinase inhibition, antioxidative and antimicrobial activies. The results from biological activity assays have shown that all of compounds have excellent antioxidant, significant tyrosinase inhibition and moderate antimicrobial activity.